Polymeric Blends and Related Optoelectronic Devices

ABSTRACT

Disclosed are all-polymer blends including an electron-acceptor polymer and an electron-donor polymer, capable of providing improved device performance, for example, as measured by power conversion efficiency, when used in photovoltaic cells.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to and the benefit of U.S. ProvisionalPatent Application Ser. No. 61/614,302, filed on Mar. 22, 2012, U.S.Provisional Patent Application Ser. No. 61/724,140, filed on Nov. 8,2012, U.S. Provisional Patent Application Ser. No. 61/733,404, filed onDec. 4, 2012, and U.S. Provisional Patent Application Ser. No.61/733,406, filed on Dec. 4, 2012, the disclosure of each of which isincorporated by reference herein in its entirety.

BACKGROUND

Organic photovoltaics (OPVs) have seen significant progress over thelast few years. A key milestone in this field has been the developmentof bulk heterojunction (BHJ) blends as the photoactive layer. In a BHJsolar cell, an electron donor (hole-transporting, p-type) semiconductormaterial and an electron acceptor (electron-transporting, n-type)semiconductor material typically are blended in solution. The mixturethen is cast via solution-phase techniques onto one of the electrodes(e.g., a high work function indium tin oxide functioning as thetransparent anode), with the donor and acceptor phases separating duringthe solvent drying process to form the BHJ photoactive layer, which hasthe morphology of a bicontinuous interpenetrating network. A low workfunction metal such as Al or Ca usually is deposited as the top layerwhich functions as the cathode. FIG. 1 illustrates a representativestructure of an OPV cell. Due to dramatically improved donor-acceptorinterfacial area, OPV cells based upon BHJ blends usually have muchbetter performance than planar bilayer structures.

While designing novel materials is critical to continued improvements inOPV device performance, recent research has been focused mainly on thedevelopment of new conjugated polymers as donor materials, with solublemolecular fullerene derivatives such as [6,6]-phenyl-C₆₁-butyric acidmethyl ester (C60PCBM or PCBM) and [6,6]-phenyl-C₇₁-butyric acid methylester (C70PCBM) remaining the dominant acceptors. Although fullerenederivatives show excellent charge separation behavior with a widevariety of donor materials and good electron transport, their absorptionin the visible and NIR region is limited. In addition, their lowestunoccupied molecular orbital (LUMO) energy level, the governing propertyfor the open circuit voltage (V_(OC)) of OPVs, is fixed and cannot beeasily adjusted. Therefore, the two major loss mechanisms in today'sOPVs are the low photocurrent (J_(SC)) due to insufficient photonabsorption and the low V_(OC) compared to the band gap of the absorbersdue to non-optimum LUMO-LUMO offset of donor and acceptor materials. Inaddition, in terms of processing, the use of an acceptor polymer(instead of a molecular acceptor like a fullerene derivative) with adonor polymer will allow more uniform films to form over large areas,hence facilitating large-scale production of OPV modules.

Efforts to replace fullerene derivatives with other organic acceptormaterials have not been very successful to date. Particularly, theapproach of using n-type polymers as acceptors in OPVs has not yieldedhigh power conversion efficiencies (PCEs) even though a range ofmaterials with good electron transporting properties and good absorptionin the visible and NIR are available. Particularly, one of theobservations is that electron-transporting or n-type polymericsemiconductors that show high performance in thin film transistor (TFT)applications do not excel necessarily as OPV acceptors. See Anthony etal., “N-Type Organic Semiconductors in Organic Electronics,” Adv.Mater., vol. 22, no. 34, pp. 3876-3892 (2010). To date, no PCE over 3%has been reported for all-polymer, fullerene-free OPVs.

For example, different groups have investigated OPVs based upon thecombination of poly(3-hexylthiophene), P3HT, as the donor material andpoly([N,N′-bis(2-octyldodecyl)-naphthalene-1,4,5,8-bis(dicarboximide)-2,6-diyl]-alt-5,5′-(2,2′-bithiophene)),P(NDI2OD-T2), as the acceptor material. First studies yielded very lowPCEs of ˜0.2%. See Moore et al., “Polymer Blend Solar Cells Based on aHigh-Mobility Naphthalenediimide-Based Polymer Acceptor Device Physics,Photophysics and Morphology,” Adv. Energy Mater., vol. 1, no. 2, pp.230-240. Significant improvements in PCE to 0.6% were achieved throughimproved processing solvent, and then to 1.4% by controlling theaggregation of P(NDI2OD-T2) through solvent mixtures and hot solventprocessing. See Fabiano et al., “Role of Photoactive Layer Morphology inHigh Fill Factor All-Polymer Bulk Heterojunction Solar Cells,” J. Mater.Chem., vol. 21, no. 16, pp. 5891-5896; and Schubert et al., “Influenceof Aggregation on the Performance of All-Polymer Solar Cells ContainingLow-Bandgap Naphthalenediimide Copolymers,” Adv. Energy. Mater., vol. 2,no. 3, pp. 369-380.

Accordingly, the art desires new polymeric blends that can enablehigh-efficiency all-polymer OPV devices.

SUMMARY

In light of the foregoing, the present teachings relate to polymericblends that include an electron-donor polymer and an electron-acceptorpolymer, where such polymeric blends can yield unexpectedly high powerconversion efficiencies in OPV devices when compared to prior artpolymeric blends.

The foregoing as well as other features and advantages of the presentteachings will be more fully understood from the following figures,description, examples, and claims.

BRIEF DESCRIPTION OF DRAWINGS

It should be understood that the drawings described below are forillustration purposes only. The drawings are not necessarily to scale,with emphasis generally being placed upon illustrating the principles ofthe present teachings. The drawings are not intended to limit the scopeof the present teachings in any way.

FIG. 1 illustrates a representative organic photovoltaic device (alsoknown as a solar cell) structure, which can incorporate the presentpolymeric blends as the photoactive layer.

DETAILED DESCRIPTION

Throughout the application, where compositions are described as having,including, or comprising specific components, or where processes aredescribed as having, including, or comprising specific process steps, itis contemplated that compositions of the present teachings also consistessentially of, or consist of, the recited components, and that theprocesses of the present teachings also consist essentially of, orconsist of, the recited process steps.

In the application, where an element or component is said to be includedin and/or selected from a list of recited elements or components, itshould be understood that the element or component can be any one of therecited elements or components, or the element or component can beselected from a group consisting of two or more of the recited elementsor components. Further, it should be understood that elements and/orfeatures of a composition, an apparatus, or a method described hereincan be combined in a variety of ways without departing from the spiritand scope of the present teachings, whether explicit or implicit herein.

The use of the terms “include,” “includes”, “including,” “have,” “has,”or “having” should be generally understood as open-ended andnon-limiting unless specifically stated otherwise.

The use of the singular herein includes the plural (and vice versa)unless specifically stated otherwise. In addition, where the use of theterm “about” is before a quantitative value, the present teachings alsoinclude the specific quantitative value itself, unless specificallystated otherwise. As used herein, the term “about” refers to a ±10%variation from the nominal value unless otherwise indicated or inferred.

It should be understood that the order of steps or order for performingcertain actions is immaterial so long as the present teachings remainoperable. Moreover, two or more steps or actions may be conductedsimultaneously.

As used herein, a component (such as a thin film layer) can beconsidered “photoactive” if it contains one or more compounds that canabsorb photons to produce excitons for the generation of a photocurrent.

As used herein, fill factor (FF) is the ratio (given as a percentage) ofthe actual maximum obtainable power, (P_(m) or V_(mp)*J_(mp)), to thetheoretical (not actually obtainable) power, (J_(sc)*V_(oc)).Accordingly, FF can be determined using the equation:

FF=(V _(mp) *J _(mp))/(J _(sc) *V _(oc))

where J_(mp) and V_(mp) represent the current density and voltage at themaximum power point (P_(m)), respectively, this point being obtained byvarying the resistance in the circuit until J*V is at its greatestvalue; and J_(sc) and V_(oc) represent the short circuit current and theopen circuit voltage, respectively. Fill factor is a key parameter inevaluating the performance of solar cells. Commercial solar cellstypically have a fill factor of about 0.60% or greater.

As used herein, the open-circuit voltage (V_(oc)) is the difference inthe electrical potentials between the anode and the cathode of a devicewhen there is no external load connected.

As used herein, the power conversion efficiency (PCE) of a solar cell isthe percentage of power converted from incident light to electricalenergy. The PCE of a solar cell can be calculated by dividing themaximum power point (P_(m)) by the input light irradiance (E, in W/m²)under standard test conditions (STC) and the surface area of the solarcell (A_(c) in m²). STC typically refers to a temperature of 25° C. andan irradiance of 1000 W/m² with an air mass 1.5 (AM 1.5) spectrum.

As used herein, a “polymeric compound” (or “polymer”) refers to amolecule including a plurality of one or more repeating units connectedby covalent chemical bonds. A polymeric compound can be represented bythe general formula:

*M*

wherein M is the repeating unit or monomer. The polymeric compound canhave only one type of repeating unit as well as two or more types ofdifferent repeating units. When a polymeric compound has only one typeof repeating unit, it can be referred to as a homopolymer. When apolymeric compound has two or more types of different repeating units,the term “copolymer” or “copolymeric compound” can be used instead. Forexample, a copolymeric compound can include repeating units

*M^(a)* and *M^(b)*,

where M^(a) and M^(b) represent two different repeating units. Unlessspecified otherwise, the assembly of the repeating units in thecopolymer can be head-to-tail, head-to-head, or tail-to-tail. Inaddition, unless specified otherwise, the copolymer can be a randomcopolymer, an alternating copolymer, or a block copolymer. For example,the general formula:

*M^(a) _(x)-M^(b) _(y)*

can be used to represent a copolymer of M^(a) and M^(b) having x molefraction of M^(a) and y mole fraction of M^(b) in the copolymer, wherethe manner in which comonomers M^(a) and M^(b) is repeated can bealternating, random, regiorandom, regioregular, or in blocks. Inaddition to its composition, a polymeric compound can be furthercharacterized by its degree of polymerization (n) and molar mass (e.g.,number average molecular weight (M_(n)) and/or weight average molecularweight (M_(w)) depending on the measuring technique(s)).

As used herein, “solution-processable” refers to compounds (e.g.,polymers), materials, or compositions that can be used in varioussolution-phase processes including spin-coating, printing (e.g., inkjetprinting, gravure printing, offset printing and the like), spraycoating, electrospray coating, drop casting, dip coating, and bladecoating.

As used herein, “halo” or “halogen” refers to fluoro, chloro, bromo, andiodo.

As used herein, “oxo” refers to a double-bonded oxygen (i.e., ═O).

As used herein, “alkyl” refers to a straight-chain or branched saturatedhydrocarbon group. Examples of alkyl groups include methyl (Me), ethyl(Et), propyl (e.g., n-propyl and iso-propyl), butyl (e.g., n-butyl,iso-butyl, sec-butyl, tert-butyl), pentyl groups (e.g., n-pentyl,iso-pentyl, neo-pentyl), hexyl groups, and the like. In variousembodiments, an alkyl group can have 1 to 40 carbon atoms (i.e., C₁₋₄₀alkyl group), for example, 1-20 carbon atoms (i.e., C₁₋₂₀ alkyl group).In some embodiments, an alkyl group can have 1 to 6 carbon atoms, andcan be referred to as a “lower alkyl group.” Examples of lower alkylgroups include methyl, ethyl, propyl (e.g., n-propyl and iso-propyl),and butyl groups (e.g., n-butyl, iso-butyl, sec-butyl, tert-butyl). Insome embodiments, alkyl groups can be substituted as described herein.An alkyl group is generally not substituted with another alkyl group, analkenyl group, or an alkynyl group.

As used herein, “haloalkyl” refers to an alkyl group having one or morehalogen substituents. At various embodiments, a haloalkyl group can have1 to 40 carbon atoms (i.e., C₁₋₄₀ haloalkyl group), for example, 1 to 20carbon atoms (i.e., C₁₋₂₀ haloalkyl group). Examples of haloalkyl groupsinclude CF₃, C₂F₅, CHF₂, CH₂F, CCl₃, CHCl₂, CH₂Cl, C₂Cl₅, and the like.Perhaloalkyl groups, i.e., alkyl groups where all of the hydrogen atomsare replaced with halogen atoms (e.g., CF₃ and C₂F₅), are includedwithin the definition of “haloalkyl.” For example, a C₁₋₄₀ haloalkylgroup can have the formula —C_(s)H_(2s+1−t)X⁰ _(t), where X⁰, at eachoccurrence, is F, Cl, Br or I, s is an integer in the range of 1 to 40,and t is an integer in the range of 1 to 81, provided that t is lessthan or equal to 2s+1. Haloalkyl groups that are not perhaloalkyl groupscan be substituted as described herein.

As used herein, “alkoxy” refers to —O-alkyl group. Examples of alkoxygroups include, but are not limited to, methoxy, ethoxy, propoxy (e.g.,n-propoxy and isopropoxy), t-butoxy, pentoxyl, hexoxyl groups, and thelike. The alkyl group in the —O-alkyl group can be substituted asdescribed herein.

As used herein, “alkylthio” refers to an —S-alkyl group. Examples ofalkylthio groups include, but are not limited to, methylthio, ethylthio,propylthio (e.g., n-propylthio and isopropylthio), t-butylthio,pentylthio, hexylthio groups, and the like. The alkyl group in the—S-alkyl group can be substituted as described herein.

As used herein, “alkenyl” refers to a straight-chain or branched alkylgroup having one or more carbon-carbon double bonds. Examples of alkenylgroups include ethenyl, propenyl, butenyl, pentenyl, hexenyl,butadienyl, pentadienyl, hexadienyl groups, and the like. The one ormore carbon-carbon double bonds can be internal (such as in 2-butene) orterminal (such as in 1-butene). In various embodiments, an alkenyl groupcan have 2 to 40 carbon atoms (i.e., C₂₋₄₀ alkenyl group), for example,2 to 20 carbon atoms (i.e., C₂₋₂₀ alkenyl group). In some embodiments,alkenyl groups can be substituted as described herein. An alkenyl groupis generally not substituted with another alkenyl group, an alkyl group,or an alkynyl group.

As used herein, “alkynyl” refers to a straight-chain or branched alkylgroup having one or more triple carbon-carbon bonds. Examples of alkynylgroups include ethynyl, propynyl, butynyl, pentynyl, hexynyl, and thelike. The one or more triple carbon-carbon bonds can be internal (suchas in 2-butyne) or terminal (such as in 1-butyne). In variousembodiments, an alkynyl group can have 2 to 40 carbon atoms (i.e., C₂₋₄₀alkynyl group), for example, 2 to 20 carbon atoms (i.e., C₂₋₂₀ alkynylgroup). In some embodiments, alkynyl groups can be substituted asdescribed herein. An alkynyl group is generally not substituted withanother alkynyl group, an alkyl group, or an alkenyl group.

As used herein, a “cyclic moiety” can include one or more (e.g., 1-6)carbocyclic or heterocyclic rings. The cyclic moiety can be a cycloalkylgroup, a heterocycloalkyl group, an aryl group, or a heteroaryl group(i.e., can include only saturated bonds, or can include one or moreunsaturated bonds regardless of aromaticity), each including, forexample, 3-24 ring atoms and optionally can be substituted as describedherein. In embodiments where the cyclic moiety is a “monocyclic moiety,”the “monocyclic moiety” can include a 3-14 membered aromatic ornon-aromatic, carbocyclic or heterocyclic ring. A monocyclic moiety caninclude, for example, a phenyl group or a 5- or 6-membered heteroarylgroup, each of which optionally can be substituted as described herein.In embodiments where the cyclic moiety is a “polycyclic moiety,” the“polycyclic moiety” can include two or more rings fused to each other(i.e., sharing a common bond) and/or connected to each other via a spiroatom, or one or more bridged atoms. A polycyclic moiety can include an8-24 membered aromatic or non-aromatic, carbocyclic or heterocyclicring, such as a C₈₋₂₄ aryl group or an 8-24 membered heteroaryl group,each of which optionally can be substituted as described herein.

As used herein, a “fused ring” or a “fused ring moiety” refers to apolycyclic ring system having at least two rings where at least one ofthe rings is aromatic and such aromatic ring (carbocyclic orheterocyclic) has a bond in common with at least one other ring that canbe aromatic or non-aromatic, and carbocyclic or heterocyclic. Thesepolycyclic ring systems can be highly π-conjugated and optionallysubstituted as described herein.

As used herein, “cycloalkyl” refers to a non-aromatic carbocyclic groupincluding cyclized alkyl, alkenyl, and alkynyl groups. In variousembodiments, a cycloalkyl group can have 3 to 24 carbon atoms, forexample, 3 to 20 carbon atoms (e.g., C₃₋₁₄ cycloalkyl group). Acycloalkyl group can be monocyclic (e.g., cyclohexyl) or polycyclic(e.g., containing fused, bridged, and/or spiro ring systems), where thecarbon atoms are located inside or outside of the ring system. Anysuitable ring position of the cycloalkyl group can be covalently linkedto the defined chemical structure. Examples of cycloalkyl groups includecyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl,cyclopentenyl, cyclohexenyl, cyclohexadienyl, cycloheptatrienyl,norbornyl, norpinyl, norcaryl, adamantyl, and spiro[4.5]decanyl groups,as well as their homologs, isomers, and the like. In some embodiments,cycloalkyl groups can be substituted as described herein.

As used herein, “heteroatom” refers to an atom of any element other thancarbon or hydrogen and includes, for example, nitrogen, oxygen, silicon,sulfur, phosphorus, and selenium.

As used herein, “cycloheteroalkyl” refers to a non-aromatic cycloalkylgroup that contains at least one ring heteroatom selected from O, S, Se,N, P, and Si (e.g., O, S, and N), and optionally contains one or moredouble or triple bonds. A cycloheteroalkyl group can have 3 to 24 ringatoms, for example, 3 to 20 ring atoms (e.g., 3-14 memberedcycloheteroalkyl group). One or more N, P, S, or Se atoms (e.g., N or S)in a cycloheteroalkyl ring may be oxidized (e.g., morpholine N-oxide,thiomorpholine S-oxide, thiomorpholine S,S-dioxide). In someembodiments, nitrogen or phosphorus atoms of cycloheteroalkyl groups canbear a substituent, for example, a hydrogen atom, an alkyl group, orother substituents as described herein. Cycloheteroalkyl groups can alsocontain one or more oxo groups, such as oxopiperidyl, oxooxazolidyl,dioxo-(1H,3H)-pyrimidyl, oxo-2(1H)-pyridyl, and the like. Examples ofcycloheteroalkyl groups include, among others, morpholinyl,thiomorpholinyl, pyranyl, imidazolidinyl, imidazolinyl, oxazolidinyl,pyrazolidinyl, pyrazolinyl, pyrrolidinyl, pyrrolinyl, tetrahydrofuranyl,tetrahydrothiophenyl, piperidinyl, piperazinyl, and the like. In someembodiments, cycloheteroalkyl groups can be substituted as describedherein.

As used herein, “aryl” refers to an aromatic monocyclic hydrocarbon ringsystem or a polycyclic ring system in which two or more aromatichydrocarbon rings are fused (i.e., having a bond in common with)together or at least one aromatic monocyclic hydrocarbon ring is fusedto one or more cycloalkyl and/or cycloheteroalkyl rings. An aryl groupcan have 6 to 24 carbon atoms in its ring system (e.g., C₆₋₂₀ arylgroup), which can include multiple fused rings. In some embodiments, apolycyclic aryl group can have 8 to 24 carbon atoms. Any suitable ringposition of the aryl group can be covalently linked to the definedchemical structure. Examples of aryl groups having only aromaticcarbocyclic ring(s) include phenyl, 1-naphthyl (bicyclic), 2-naphthyl(bicyclic), anthracenyl (tricyclic), phenanthrenyl (tricyclic),pentacenyl (pentacyclic), and like groups. Examples of polycyclic ringsystems in which at least one aromatic carbocyclic ring is fused to oneor more cycloalkyl and/or cycloheteroalkyl rings include, among others,benzo derivatives of cyclopentane (i.e., an indanyl group, which is a5,6-bicyclic cycloalkyl/aromatic ring system), cyclohexane (i.e., atetrahydronaphthyl group, which is a 6,6-bicyclic cycloalkyl/aromaticring system), imidazoline (i.e., a benzimidazolinyl group, which is a5,6-bicyclic cycloheteroalkyl/aromatic ring system), and pyran (i.e., achromenyl group, which is a 6,6-bicyclic cycloheteroalkyl/aromatic ringsystem). Other examples of aryl groups include benzodioxanyl,benzodioxolyl, chromanyl, indolinyl groups, and the like. In someembodiments, aryl groups can be substituted as described herein. In someembodiments, an aryl group can have one or more halogen substituents,and can be referred to as a “haloaryl” group. Perhaloaryl groups, i.e.,aryl groups where all of the hydrogen atoms are replaced with halogenatoms (e.g., —C₆F₅), are included within the definition of “haloaryl.”In certain embodiments, an aryl group is substituted with another arylgroup and can be referred to as a biaryl group. Each of the aryl groupsin the biaryl group can be substituted as disclosed herein.

As used herein, “arylalkyl” refers to an -alkyl-aryl group, where thearylalkyl group is covalently linked to the defined chemical structurevia the alkyl group. An arylalkyl group is within the definition of a—Y—C₆₋₁₄ aryl group, where Y is as defined herein. An example of anarylalkyl group is a benzyl group (—CH₂—C₆H₅). An arylalkyl group can beoptionally substituted, i.e., the aryl group and/or the alkyl group, canbe substituted as disclosed herein.

As used herein, “heteroaryl” refers to an aromatic monocyclic ringsystem containing at least one ring heteroatom selected from oxygen (O),nitrogen (N), sulfur (S), silicon (Si), and selenium (Se) or apolycyclic ring system where at least one of the rings present in thering system is aromatic and contains at least one ring heteroatom.Polycyclic heteroaryl groups include those having two or more heteroarylrings fused together, as well as those having at least one monocyclicheteroaryl ring fused to one or more aromatic carbocyclic rings,non-aromatic carbocyclic rings, and/or non-aromatic cycloheteroalkylrings. A heteroaryl group, as a whole, can have, for example, 5 to 24ring atoms and contain 1-5 ring heteroatoms (i.e., 5-20 memberedheteroaryl group). The heteroaryl group can be attached to the definedchemical structure at any heteroatom or carbon atom that results in astable structure. Generally, heteroaryl rings do not contain O—O, S—S,or S—O bonds. However, one or more N or S atoms in a heteroaryl groupcan be oxidized (e.g., pyridine N-oxide, thiophene S-oxide, thiopheneS,S-dioxide). Examples of heteroaryl groups include, for example, the 5-or 6-membered monocyclic and 5-6 bicyclic ring systems shown below:

where T is O, S, NH, N-alkyl, N-aryl, N-(arylalkyl) (e.g., N-benzyl),SiH₂, SiH(alkyl), Si(alkyl)₂, SiH(arylalkyl), Si(arylalkyl)₂, orSi(alkyl)(arylalkyl). Examples of such heteroaryl rings includepyrrolyl, furyl, thienyl, pyridyl, pyrimidyl, pyridazinyl, pyrazinyl,triazolyl, tetrazolyl, pyrazolyl, imidazolyl, isothiazolyl, thiazolyl,thiadiazolyl, isoxazolyl, oxazolyl, oxadiazolyl, indolyl, isoindolyl,benzofuryl, benzothienyl, quinolyl, 2-methylquinolyl, isoquinolyl,quinoxalyl, quinazolyl, benzotriazolyl, benzimidazolyl, benzothiazolyl,benzisothiazolyl, benzisoxazolyl, benzoxadiazolyl, benzoxazolyl,cinnolinyl, 1H-indazolyl, 2H-indazolyl, indolizinyl, isobenzofuyl,naphthyridinyl, phthalazinyl, pteridinyl, purinyl, oxazolopyridinyl,thiazolopyridinyl, imidazopyridinyl, furopyridinyl, thienopyridinyl,pyridopyrimidinyl, pyridopyrazinyl, pyridopyridazinyl, thienothiazolyl,thienoxazolyl, thienoimidazolyl groups, and the like. Further examplesof heteroaryl groups include 4,5,6,7-tetrahydroindolyl,tetrahydroquinolinyl, benzothienopyridinyl, benzofuropyridinyl groups,and the like. In some embodiments, heteroaryl groups can be substitutedas described herein.

Compounds of the present teachings can include a “divalent group”defined herein as a linking group capable of forming a covalent bondwith two other moieties. For example, compounds of the present teachingscan include a divalent C₁₋₂₀ alkyl group (e.g., a methylene group), adivalent C₂₋₂₀ alkenyl group (e.g., a vinylyl group), a divalent C₂₋₂₀alkynyl group (e.g., an ethynylyl group). a divalent C₆₋₁₄ aryl group(e.g., a phenylyl group); a divalent 3-14 membered cycloheteroalkylgroup (e.g., a pyrrolidylyl), and/or a divalent 5-14 membered heteroarylgroup (e.g., a thienylyl group). Generally, a chemical group (e.g.,-Ar-) is understood to be divalent by the inclusion of the two bondsbefore and after the group.

The electron-donating or electron-withdrawing properties of severalhundred of the most common substituents, reflecting all common classesof substituents have been determined, quantified, and published. Themost common quantification of electron-donating and electron-withdrawingproperties is in terms of Hammett σ values. Hydrogen has a Hammett σvalue of zero, while other substituents have Hammett σ values thatincrease positively or negatively in direct relation to theirelectron-withdrawing or electron-donating characteristics. Substituentswith negative Hammett σ values are considered electron-donating, whilethose with positive Hammett σ values are consideredelectron-withdrawing. See Lange's Handbook of Chemistry, 12th ed.,McGraw Hill, 1979, Table 3-12, pp. 3-134 to 3-138, which lists Hammett σvalues for a large number of commonly encountered substituents and isincorporated by reference herein.

It should be understood that the term “electron-accepting group” can beused synonymously herein with “electron acceptor” and“electron-withdrawing group”. In particular, an “electron-withdrawinggroup” (“EWG”) or an “electron-accepting group” or an“electron-acceptor” refers to a functional group that draws electrons toitself more than a hydrogen atom would if it occupied the same positionin a molecule. Examples of electron-withdrawing groups include, but arenot limited to, halogen or halo (e.g., F, Cl, Br, I), —NO₂, —CN, —NC,—S(R⁰)₂ ⁺, —N(R⁰)₃ ⁺, —SO₃H, —SO₂R⁰, —SO₃R⁰, —SO₂NHR⁰, —SO₂N(R⁰)₂,—COOH, —COR⁰, —COOR⁰, —CONHR⁰, —CON(R⁰)₂, C₁₋₄₀ haloalkyl groups, C₆₋₁₄aryl groups, and 5-14 membered electron-poor heteroaryl groups; where R⁰is a C₁₋₂₀ alkyl group, a C₂₋₂₀ alkenyl group, a C₂₋₂₀ alkynyl group, aC₁₋₂₀ haloalkyl group, a C₁₋₂₀ alkoxy group, a C₆₋₁₄ aryl group, a C₃₋₁₄cycloalkyl group, a 3-14 membered cycloheteroalkyl group, and a 5-14membered heteroaryl group, each of which can be optionally substitutedas described herein. For example, each of the C₁₋₂₀ alkyl group, theC₂₋₂₀ alkenyl group, the C₂₋₂₀ alkynyl group, the C₁₋₂₀ haloalkyl group,the C₁₋₂₀ alkoxy group, the C₆₋₁₄ aryl group, the C₃₋₁₄ cycloalkylgroup, the 3-14 membered cycloheteroalkyl group, and the 5-14 memberedheteroaryl group can be optionally substituted with 1-5 smallelectron-withdrawing groups such as F, Cl, Br, —NO₂, —CN, —NC, —S(R⁰)₂⁺, —N(R⁰)₃ ⁺, —SO₃H, —SO₂R⁰, —SO₃R⁰, —SO₂NHR⁰, —SO₂N(R⁰)₂, —COOH, —COR⁰,—COOR⁰, —CONHR⁰, and —CON(R)₂.

It should be understood that the term “electron-donating group” can beused synonymously herein with “electron donor”. In particular, an“electron-donating group” or an “electron-donor” refers to a functionalgroup that donates electrons to a neighboring atom more than a hydrogenatom would if it occupied the same position in a molecule. Examples ofelectron-donating groups include —OH, —OR⁰, —NH₂, —NHR⁰, —N(R⁰)₂, and5-14 membered electron-rich heteroaryl groups, where R⁰ is a C₁₋₂₀ alkylgroup, a C₂₋₂₀ alkenyl group, a C₂₋₂₀ alkynyl group, a C₆₋₁₄ aryl group,or a C₃₋₁₄ cycloalkyl group.

Various unsubstituted heteroaryl groups can be described aselectron-rich (or π-excessive) or electron-poor (or π-deficient). Suchclassification is based on the average electron density on each ringatom as compared to that of a carbon atom in benzene. Examples ofelectron-rich systems include 5-membered heteroaryl groups having oneheteroatom such as furan, pyrrole, and thiophene; and their benzofusedcounterparts such as benzofuran, benzopyrrole, and benzothiophene.Examples of electron-poor systems include 6-membered heteroaryl groupshaving one or more heteroatoms such as pyridine, pyrazine, pyridazine,and pyrimidine; as well as their benzofused counterparts such asquinoline, isoquinoline, quinoxaline, cinnoline, phthalazine,naphthyridine, quinazoline, phenanthridine, acridine, and purine. Mixedheteroaromatic rings can belong to either class depending on the type,number, and position of the one or more heteroatom(s) in the ring. SeeKatritzky, A. R and Lagowski, J. M., Heterocyclic Chemistry (John Wiley& Sons, New York, 1960).

At various places in the present specification, substituents aredisclosed in groups or in ranges. It is specifically intended that thedescription include each and every individual subcombination of themembers of such groups and ranges. For example, the term “C₁₋₆ alkyl” isspecifically intended to individually disclose C₁, C₂, C₃, C₄, C₅, C₆,C₁-C₆, C₁-C₅, C₁-C₄, C₁-C₃, C₁-C₂, C₂-C₆, C₂-C₅, C₂-C₄, C₂-C₃, C₃-C₆,C₃-C₅, C₃-C₄, C₄-C₆, C₄-C₅, and C₅-C₆ alkyl. By way of other examples,an integer in the range of 0 to 40 is specifically intended toindividually disclose 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14,15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32,33, 34, 35, 36, 37, 38, 39, and 40, and an integer in the range of 1 to20 is specifically intended to individually disclose 1, 2, 3, 4, 5, 6,7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, and 20. Additionalexamples include that the phrase “optionally substituted with 1-5substituents” is specifically intended to individually disclose achemical group that can include 0, 1, 2, 3, 4, 5, 0-5, 0-4, 0-3, 0-2,0-1, 1-5, 1-4, 1-3, 1-2, 2-5, 2-4, 2-3, 3-5, 3-4, and 4-5 substituents.

Compounds described herein can contain an asymmetric atom (also referredas a chiral center) and some of the compounds can contain two or moreasymmetric atoms or centers, which can thus give rise to optical isomers(enantiomers) and geometric isomers (diastereomers). The presentteachings include such optical and geometric isomers, including theirrespective resolved enantiomerically or diastereomerically pure isomers(e.g., (+) or (−) stereoisomer) and their racemic mixtures, as well asother mixtures of the enantiomers and diastereomers. In someembodiments, optical isomers can be obtained in enantiomericallyenriched or pure form by standard procedures known to those skilled inthe art, which include, for example, chiral separation, diastereomericsalt formation, kinetic resolution, and asymmetric synthesis. Thepresent teachings also encompass cis- and trans-isomers of compoundscontaining alkenyl moieties (e.g., alkenes, azo, and imines). It alsoshould be understood that the compounds of the present teachingsencompass all possible regioisomers in pure form and mixtures thereof.In some embodiments, the preparation of the present compounds caninclude separating such isomers using standard separation proceduresknown to those skilled in the art, for example, by using one or more ofcolumn chromatography, thin-layer chromatography, simulated moving-bedchromatography, and high-performance liquid chromatography. However,mixtures of regioisomers can be used similarly to the uses of eachindividual regioisomer of the present teachings as described hereinand/or known by a skilled artisan.

It is specifically contemplated that the depiction of one regioisomerincludes any other regioisomers and any regioisomeric mixtures unlessspecifically stated otherwise.

As used herein, a “leaving group” (“LG”) refers to a charged oruncharged atom (or group of atoms) that can be displaced as a stablespecies as a result of, for example, a substitution or eliminationreaction. Examples of leaving groups include, but are not limited to,halogen (e.g., Cl, Br, I), azide (N₃), thiocyanate (SCN), nitro (NO₂),cyanate (CN), water (H₂O), ammonia (NH₃), and sulfonate groups (e.g.,OSO₂—R, wherein R can be a C₁₋₁₀ alkyl group or a C₆₋₁₄ aryl group eachoptionally substituted with 1-4 groups independently selected from aC₁₋₁₀ alkyl group and an electron-withdrawing group) such as tosylate(toluenesulfonate, OTs), mesylate (methanesulfonate, OMs), brosylate(p-bromobenzenesulfonate, OBs), nosylate (4-nitrobenzenesulfonate, ONs),and triflate (trifluoromethanesulfonate, OTf).

Throughout the specification, structures may or may not be presentedwith chemical names. Where any question arises as to nomenclature, thestructure prevails.

The present teachings relate to polymer-polymer blend semiconductormaterials that include an electron-donor polymer and anelectron-acceptor polymer, where the polymer-polymer blend semiconductormaterials can provide unexpectedly high power conversion efficiencies(PCEs) when used as the photoactive layer in optoelectronic devices suchas OPV cells. More specifically, both the electron-acceptor polymer andthe electron-donor polymer can be described as π-conjugated polymers,where repeat units in the polymer backbone are made up of atoms with sp²and π covalent bonds resulting in alternating double and single bondsalong the polymer backbone. The electron-acceptor polymer and theelectron-donor polymer have different electron affinities and opticalenergy gaps. Specifically, the electron-donor polymer has a lowerelectron affinity (or lower ionization energy) than theelectron-acceptor polymer and therefore functions as a p-type(hole-transporting) conduction area in the blend. Conversely, theelectron-acceptor polymer has a higher electron affinity (or higherionization energy) than the electron-donor polymer and thereforefunctions as an n-type (electron-transporting) conduction area in theblend. In addition, the electron-acceptor polymer can be characterizedby both a lower E_(HOMO) (highest occupied molecular orbital energylevel) and a lower E_(LUMO) (lowest unoccupied molecular orbital energy)that those of the electron-donor polymer. In preferred embodiments, theE_(HOMO) of the electron-acceptor polymer can be at least about −0.3 eVlower than the E_(HOMO) of the electron-donor polymer, while theE_(LUMO) of the electron-acceptor polymer can be about at least about−0.3 eV lower than the E_(LUMO) of the electron-donor polymer.

The inventors have discovered that various embodiments of apolymer-polymer blend (“all-polymer blend”) that include anelectron-transporting polymer which is a copolymer comprising anaromatic fused-ring diimide unit in its backbone, and ahole-transporting polymer which is a copolymer comprising one or morethienyl or thienothienyl units and at least one electron-poor unit inits backbone, unexpectedly can lead to power conversion efficiencies(PCEs) greater than about 3.0% when incorporated as the photoactivelayer in OPV cells. The electron-transporting polymer is referred hereininterchangeably as the electron-acceptor polymer, while thehole-transporting polymer is referred herein interchangeably as theelectron-donor polymer. The electron-transporting polymer typicallyexhibits an electron mobility greater than about 10⁻⁵ cm²/Vs,preferably, greater than about 10⁻³ cm²/Vs, and more preferably, greaterthan about 10⁻² cm²/Vs; while the hole-transporting polymer typicallyexhibits a hole mobility greater than about 10⁻⁵ cm²/Vs, preferably,greater than about 10⁻³ cm²/Vs, and more preferably, greater than about10⁻² cm²/Vs. Particularly, while poly(3-hexylthiophene) has beeninvestigated as an electron-donor polymer in certain all-polymerphotovoltaic devices, to the inventors' knowledge, there has been noreport to date of any all-polymer photovoltaic devices with a powerconversion efficiency (PCEs) greater than about 3.0% which includes anelectron-donor polymer comprising one or more electron-poor units. Asdescribed in more detailed below, the electron-poor unit can be selectedfrom an electron-poor 8-20 membered polycyclic heteroaryl group and achlorinated 5-20 membered heteroaryl group. Without wishing to be boundby any particular theory, it is believed that the unexpectedly highpower conversion efficiencies can be a result of advantageousdonor/acceptor pairing in terms of a low bandgap between the HOMO of thedonor polymer and the LUMO of the acceptor polymer, fine-tuned LUMO-LUMOenergy offset, combined optical absorption across the solar spectrum,and/or improved charge transport characteristics due to optimized blendmorphology/microstructure relating to favorable intermolecularinteraction between the donor polymer and the acceptor polymer.

The aromatic fused-ring diimide-based acceptor polymer in the presentpolymer-polymer blend can be an alternating or random copolymer wherethe other repeat unit(s) (i.e., the repeat unit(s) that do not includeany aromatic fused-ring diimides) can include one or more conjugatedmoieties such as one or more monocyclic or polycyclic C₆₋₂₀ arylmoieties or 5-20 membered heteroaryl moieties. A aromatic fused-ringdiimide may be referred herein interchangeably as a bis(imide)areneunit. In certain embodiments, the aromatic fused-ring diimide-basedacceptor polymer can be an alternating polymer represented by Formula 1:

wherein:π-1 is an optionally substituted fused ring moiety;R¹ is selected from the group consisting of a C₁₋₃₀ alkyl group, a C₂₋₃₀alkenyl group, a C₁₋₃₀ haloalkyl group, a C₆₋₂₀ aryl group and a 5-14membered heteroaryl group, wherein the C₆₋₂₀ aryl group and the 5-14membered heteroaryl group optionally are substituted with a C₁₋₃₀ alkylgroup, a C₂₋₃₀ alkenyl group, or a C₁₋₃₀ haloalkyl group;M^(a) is a repeat unit comprising one or more conjugated moieties thatdoes not include a rylene diimide; andn is an integer in the range of 2 to 5,000.

In certain embodiments, the aromatic fused-ring diimide-based acceptorpolymer can be a random polymer represented by Formula 2:

wherein:π-1 and π-1′ can be identical or different and independently are anoptionally substituted fused ring moiety;

R¹ and R^(1′) can be identical or different and independently areselected from the group consisting of a C₁₋₃₀ alkyl group, a C₂₋₃₀alkenyl group, a C₁₋₃₀ haloalkyl group, a C₆₋₂₀ aryl group and a 5-14membered heteroaryl group, wherein the C₆₋₂₀ aryl group and the 5-14membered heteroaryl group optionally are substituted with a C₁₋₃₀ alkylgroup, a C₂₋₃₀ alkenyl group, or a C₁₋₃₀ haloalkyl group;

M^(a) and M^(a′) can be identical or different and independently are arepeat unit comprising one or more conjugated moieties that does notinclude a rylene diimide;p and q independently are a real number, wherein 0.1≦p≦0.9, 0.1≦q≦0.9,and the sum of p and q is about 1; andn is an integer in the range of 2 to 5,000;provided that at least one of the following is true: (a) π-1′ isdifferent from π-1, (b) R^(1′) is different from R¹, or (c) M^(a′) isdifferent from M^(a).

In various embodiments, the aromatic fused-ring diimide can be selectedfrom the group consisting of a perylene diimide, a naphthalene diimide,an anthracene diimide, a coronene diimide, and a dithienocoronenediimide, with π-1 and π-1′ independently being a fused ring moietyselected from the group consisting of:

The one or more conjugated moieties in the co-repeat unit M^(a) andM^(a′) can be represented by Ar, π-2, and Z, wherein Ar is an optionallysubstituted monocyclic aryl or heteroaryl group, π-2 is an optionallysubstituted polycyclic conjugated moiety, and Z is a conjugated linearlinker. In various embodiments, M^(a) and M^(a′) can have a formulaselected from:

wherein m, m′ and m″ independently are 0, 1, 2, 3, 4, 5 or 6.

For example, in some embodiments, π-2 can be a polycyclic C₈₋₂₄ arylgroup or a polycyclic 8-24 membered heteroaryl group, wherein each ofthese groups can be optionally substituted with 1-6 R^(e) groups,wherein:

-   -   R^(e), at each occurrence, is independently a) halogen, b)        —CN, c) —NO₂, d) oxo, e) —OH, f) ═C(R^(f))₂, g) a C₁₋₄₀ alkyl        group, h) a C₂₋₄₀ alkenyl group, i) a C₂₋₄₀ alkynyl group, j) a        C₁₋₄₀ alkoxy group, k) a C₁₋₄₀ alkylthio group, l) a C₁₋₄₀        haloalkyl group, m) a —Y—C₃₋₁₀ cycloalkyl group, n) a —Y—C₆₋₁₄        aryl group, o) a —Y—C₆₋₁₄ haloaryl group, p) a —Y-3-12 membered        cycloheteroalkyl group, or q) a —Y-5-14 membered heteroaryl        group, wherein each of the C₁₋₄₀ alkyl group, the C₂₋₄₀ alkenyl        group, the C₂₋₄₀ alkynyl group, the C₃₋₁₀ cycloalkyl group, the        C₆₋₁₄ aryl group, the C₆₋₁₄ haloaryl group, the 3-12 membered        cycloheteroalkyl group, and the 5-14 membered heteroaryl group        is optionally substituted with 1-4 R^(f) groups;    -   R^(f), at each occurrence, is independently a) halogen, b)        —CN, c) —NO₂, d) oxo, e) —OH, f) —NH₂, g) —NH(C₁₋₂₀ alkyl), h)        —N(C₁₋₂₀ alkyl)₂, i) —N(C₁₋₂₀ alkyl)-C₆₋₁₄ aryl, j) —N(C₆₋₁₄        aryl)₂, k) —S(O)_(w)H, 1) —S(O)_(w)—C₁₋₂₀ alkyl, m) —S(O)₂OH, n)        —S(O)_(w)—OC₁₋₂₀ alkyl, o) —S(O)_(w)—OC₆₋₁₄ aryl, p) —CHO, q)        —C(O)—C₁₋₂₀ alkyl, r) —C(O)—C₆₋₁₄ aryl, s) —C(O)OH, t)        —C(O)—OC₁₋₂₀ alkyl, u) —C(O)—OC₆₋₁₄ aryl, v) —C(O)NH₂, w)        —C(O)NH—C₁₋₂₀ alkyl, x) —C(O)N(C₁₋₂₀ alkyl)₂, y) —C(O)NH—C₆₋₁₄        aryl, z) —C(O)N(C₁₋₂₀ alkyl)-C₆₋₁₄ aryl, aa) —C(O)N(C₆₋₁₄        aryl)₂, ab) —C(S)NH₂, ac) —C(S)NH—C₁₋₂₀ alkyl, ad) —C(S)N(C₁₋₂₀        alkyl)₂, ae) —C(S)N(C₆₋₁₄ aryl)₂, af) —C(S)N(C₁₋₂₀ alkyl)-C₆₋₁₄        aryl, ag) —C(S)NH—C₆₋₁₄ aryl, ah) —S(O)_(w)NH₂, ai)        —S(O)_(w)NH(C₁₋₂₀ alkyl), aj) —S(O)_(w)N(C₁₋₂₀ alkyl)₂, ak)        —S(O)_(w)NH(C₆₋₁₄ aryl), al) —S(O)_(w)N(C₁₋₂₀ alkyl)-C₆₋₁₄ aryl,        am) —S(O)_(w)N(C₆₋₁₄ aryl)₂, an) —SiH₃, ao) —SiH(C₁₋₂₀ alkyl)₂,        ap) —SiH₂(C₁₋₂₀ alkyl), aq) —Si(C₁₋₂₀ alkyl)₃, ar) a C₁₋₂₀ alkyl        group, as) a C₂₋₂₀ alkenyl group, at) a C₂₋₂₀ alkynyl group, au)        a C₁₋₂₀ alkoxy group, av) a C₁₋₂₀ alkylthio group, aw) a C₁₋₂₀        haloalkyl group, ax) a C₃₋₁₀ cycloalkyl group, ay) a C₆₋₁₄ aryl        group, az) a C₆₋₁₄ haloaryl group, ba) a 3-12 membered        cycloheteroalkyl group, or bb) a 5-14 membered heteroaryl group;    -   Y, at each occurrence, is independently selected from a divalent        C₁₋₆ alkyl group, a divalent C₁₋₆ haloalkyl group, and a        covalent bond; and    -   w is 0, 1, or 2.

To illustrate, in certain embodiments, π-2 can be selected from:

wherein:k, k′, l and l′ independently can be selected from —CR²═, ═CR²—, —C(O)—,and —C(C(CN)₂)—;p, p′, q and q′ independently can be selected from —CR²═, ═CR²—, —C(O)—,—C(C(CN)₂)—, —O—, —S—, —N═, ═N—, —N(R²)—, —SiR²═, ═SiR²—, and —SiR²R²—;r and s independently can be —CR²R²— or —C(C(CN)₂)—;u, u′, v and v′ independently can be selected from —CR²═, ═CR²—, —C(O)—,—C(C(CN)₂)—, —S—, —S(O)—, —S(O)₂, —O—, —N═, ═N—, —SiR²═, ═SiR²—,—SiR²R²—, —CR²R²—CR²R²—, and —CR²═CR²—; andR², at each occurrence, independently can be H or R^(e), wherein R^(e)is as defined herein.

In certain embodiments, π-2 can be selected from:

where k, l, p, p′, q, q′, r, s and R² are as defined herein. In someembodiments, k and l independently can be selected from —CR²═, ═CR²—,and —C(O)—; p, p′, q, and q′ independently can be selected from —O—,—S—, —N(R²)—, —N═, ═N—, —CR²═, and ═CR²—; u and v independently can beselected from —CR²═, ═CR²—, —C(O)—, —C(C(CN)₂)—, —S—, —O—, —N═, ═N—,—CR²R²—CR²R²—, and —CR²═CR²—; where R² is as defined herein. Forexample, R², at each occurrence, independently can be selected from H, ahalogen, —CN, —OR^(c), —N(R^(c))₂, a C₁₋₂₀ alkyl group, and a C₁₋₂₀haloalkyl group, where R^(c) is as defined herein. Each of r and s canbe CH₂.

In certain embodiments, π-2 can be a polycyclic moiety including one ormore thienyl, thiazolyl, or phenyl groups, where each of these groupscan be optionally substituted as disclosed herein. For example, π-2 canbe selected from:

wherein R² is as defined herein. For example, R² can be selected from H,a C₁₋₂₀ alkyl group, a C₁₋₂₀ alkoxy group, and a C₁₋₂₀ haloalkyl group.

In some embodiments, Ar, at each occurrence, independently can be anoptionally substituted monocyclic moiety selected from:

wherein:a, b, c and d independently are selected from —S—, —O—, —CH═, ═CH—,—CR³—, ═CR³—, —C(O)—, —C(C(CN)₂)—, —N═, ═N—, —NH— and —NR³—;R³, at each occurrence, is independently selected from a) halogen, b)—CN, c) —NO₂, d) —N(R^(c))₂, e) —OR^(c), f) —C(O)R^(c), g) —C(O)OR^(c),h) —C(O)N(R^(c))₂, i) a C₁₋₄₀ alkyl group, j) a C₂₋₄₀ alkenyl group, k)a C₂₋₄₀ alkynyl group, l) a C₁₋₄₀ alkoxy group, m) a C₁₋₄₀ alkylthiogroup, n) a C₁₋₄₀ haloalkyl group, o) a —Y—C₃₋₁₄ cycloalkyl group, p) a—Y—C₆₋₁₄ aryl group, q) a —Y-3-14 membered cycloheteroalkyl group, andr) a —Y-5-14 membered heteroaryl group, wherein each of the C₁₋₄₀ alkylgroup, the C₂₋₄₀ alkenyl group, the C₂₋₄₀ alkynyl group, the C₃₋₁₄cycloalkyl group, the C₆₋₁₄ aryl group, the 3-14 memberedcycloheteroalkyl group, and the 5-14 membered heteroaryl groupoptionally is substituted with 1-5 R^(e) groups;R^(c), at each occurrence, is independently selected from H, a C₁₋₆alkyl group, and a —Y—C₆₋₁₄ aryl group;Y and R^(e) are as defined herein.

In certain embodiments, each Ar can be independently a 5- or 6-memberedaryl or heteroaryl group. For example, each Ar can be selected from aphenyl group, a thienyl group, a furyl group, a pyrrolyl group, anisothiazolyl group, a thiazolyl group, a 1,2,4-thiadiazolyl group, a1,3,4-thiadiazolyl group, and a 1,2,5-thiadiazolyl group, wherein eachgroup can be divalent or monovalent, and optionally can be substitutedwith 1-4 substituents independently selected from a halogen, —CN, an oxogroup, a C₁₋₆ alkyl group, a C₁₋₆ alkoxy group, a C₁₋₆ haloalkyl group,NH₂, NH(C₁₋₆ alkyl) and N(C₁₋₆alkyl)₂. In particular embodiments, eachAr can be selected from a thienyl group, an isothiazolyl group, athiazolyl group, a 1,2,4-thiadiazolyl group, a 1,3,4-thiadiazolyl group,a 1,2,5-thiadiazolyl group, a phenyl group, and a pyrrolyl group,wherein each group optionally can be substituted with 1-2 substituentsindependently selected from a halogen, —CN, an oxo group, a C₁₋₆ alkylgroup, a C₁₋₆ alkoxy group, a C₁₋₆ haloalkyl group, NH₂, NH(C₁₋₆ alkyl)and N(C₁₋₆alkyl)₂. In some embodiments, Ar can be unsubstituted. In someembodiments, Ar can be a thienyl group, an isothiazolyl group, athiazolyl group, a 1,2,4-thiadiazolyl group, a 1,3,4-thiadiazolyl group,and a 1,2,5-thiadiazolyl group, wherein each optionally is substitutedwith 1-2 C₁₋₆ alkyl groups.

By way of example, (Ar)_(m), (Ar)_(m′), and (Ar)_(m′) can be selectedfrom:

wherein R⁴, at each occurrence, independently is H or R³, and R³ is asdefined herein. In particular embodiments,

can be selected from:

wherein R^(c) is as defined herein.

In various embodiments, the linker Z can be a conjugated system byitself (e.g., including two or more double or triple bonds) or can forma conjugated system with its neighboring components. For example, inembodiments where Z is a linear linker, Z can be a divalent ethenylgroup (i.e., having one double bond), a divalent ethynyl group (i.e.,having one tripe bond), a C₄₋₄₀ alkenyl or alkynyl group that includestwo or more conjugated double or triple bonds, or some other non-cyclicconjugated systems that can include heteroatoms such as Si, N, P, andthe like. For example, Z can be selected from:

wherein R⁴ is as defined herein. In certain embodiments, Z can beselected from:

In some embodiments, M^(a) and M^(a′) can include at least oneoptionally substituted monocylic aryl or heteroaryl group. For example,M^(a) and M^(a′) can have the formula:

wherein m″ is selected from 1, 2, 3, 4, 5, or 6; and Ar is as definedherein. For example, M^(a) and M^(a′) can be selected from:

wherein R³ and R⁴ are as defined herein. In particular embodiments,M^(a) and M^(a′) can be selected from:

wherein R³ can be independently selected from a halogen, —CN, a C₁₋₂₀alkyl group, a C₁₋₂₀ alkoxy group, and a C₁₋₂₀ haloalkyl group; R⁴ canbe independently selected from H, a halogen, —CN, a C₁₋₂₀ alkyl group, aC₁₋₂₀ alkoxy group, and a C₁₋₂₀ haloalkyl group; and R^(c), at eachoccurrence, can be independently H or a C₁₋₆ alkyl group.

In some embodiments, M^(a) and M^(a′), in addition to the one or moreoptionally substituted monocyclic aryl or heteroaryl group, can includea linker. For example, M^(a) and M^(a′) can have the formula:

wherein m and m′ are selected from 1, 2, 4, or 6; m″ is selected from 1,2, 3, or 4; and Ar and Z are as defined herein. In certain embodiments,M^(a) and M^(a′) can be selected from:

wherein R⁴ and R^(c) are as defined herein.

In some embodiments, M^(a) and M^(a′), in addition to the one or moreoptionally substituted monocyclic aryl or heteroaryl group, can includeone or more optionally substituted polycyclic moieties. For example,M^(a) and M^(a′) can have the formula:

wherein m and m′ are selected from 1, 2, 4, or 6; and Ar and π-2 are asdefined herein. In certain embodiments, M^(a) and M^(a′) can be selectedfrom:

wherein R² and R⁴ are as defined herein.

In some embodiments, M^(a) and M^(a′), in addition to the one or moreoptionally substituted monocyclic aryl or heteroaryl group, can includeone or more linkers and/or optionally substituted polycyclic moieties.For example, M^(a) and M^(a′) can have a formula selected from:

wherein m, m′ and m″ independently are 1, 2, 3 or 4; and Ar, π-2 and Zare as defined herein. In certain embodiments, M^(a) and M^(a′) can beselected from

wherein R⁴ is as defined herein.

In other embodiments, M^(a) and M^(a′) can have a formula selected from:

wherein π-2 and Z are as defined herein.

To illustrate, M^(a) and M^(a′) can be selected from the groupconsisting of:

wherein g, h, i and j independently can be selected from —CR²═, ═CR²,—S—, —N═, ═N—, and —N(R²)—; R² and R, at each occurrence, independentlycan be H or R^(e); and R^(e) is as defined herein.

In particular embodiments, the electron-acceptor polymer of the presentpolymer-polymer blend can be represented by Formula 3 or 4:

wherein:π-1 and π-1′ can be identical or different and independently are anoptionally substituted fused ring moiety;

R¹ and R^(1′) can be identical or different and independently areselected from the group consisting of a C₁₋₃₀ alkyl group, a C₂₋₃₀alkenyl group, a C₁₋₃₀ haloalkyl group, a C₆₋₂₀ aryl group and a 5-14membered heteroaryl group, wherein the C₆₋₂₀ aryl group and the 5-14membered heteroaryl group optionally are substituted with a C₁₋₃₀ alkylgroup, a C₂₋₃₀ alkenyl group, or a C₁₋₃₀ haloalkyl group;

R′ and R″ can be identical or different and independently are selectedfrom the group consisting of H, F, Cl, —CN, and -L-R, wherein L, at eachoccurrence, independently is selected from the group consisting of —O—,—S—, —C(O), —C(O)O—, and a covalent bond; and R, at each occurrence,independently can be selected from the group consisting of a C₆₋₂₀ alkylgroup, a C₆₋₂₀ alkenyl group, and a C₆₋₂₀ haloalkyl group;

m and m′ independently can be 1, 2, 3, 4, 5 or 6; andp and q independently are a real number, wherein 0.1≦p≦0.9, 0.1≦q≦0.9,and the sum of p and q is about 1; andn is an integer in the range of 2 to 5,000;provided that at least one of the following is true: (a) π-1′ isdifferent from π-1, (b) R^(1′) is different from R¹, or (c) R″ isdifferent from R′.

To illustrate further, embodiments of the electron-acceptor polymer ofthe present polymer-polymer blend can be represented by Formula 5, 6, 7,or 8:

wherein R¹, R^(1′), p, q, and n are as defined herein.

For example, R¹ and R^(1′) can be selected from the group consisting ofa branched C₃₋₂₀ alkyl group, a branched C₄₋₂₀ alkenyl group, and abranched C₃₋₂₀ haloalkyl group such as:

The donor polymer in the present polymer-polymer blend can have analternating push-pull structure represented by formula 9:

*D-A*  (9),

where the donor subunit (D) includes a bridged dithiophene moietyselected from the group consisting of a benzodithiophene moiety, anaphthodithiophene moiety, a thienodithiophene moiety, and apyridodithiophene moiety; the acceptor subunit (A) includes anelectron-poor conjugated moiety; and either the donor subunit (D) or theacceptor subunit (A) comprises one or more thienyl or thienothienylgroups. For example, the bridged dithiophene moiety of the donor subunit(D) can be selected from the group consisting of:

where R^(a), at each occurrence, independently can be selected from thegroup consisting of -L′-R^(b), -L′-Ar′, and -L′-Ar′-Ar′, where L′ isselected from the group consisting of —O—, —S—, —C(O)O—, —OC(O)—, and acovalent bond; R^(b) is selected from the group consisting of a C₃₋₄₀alkyl group, a C₃₋₄₀ alkenyl group, and a C₃₋₄₀ haloalkyl group; andAr′, at each occurrence, independently is a 5-14 membered heteroarylgroup optionally substituted with 1-2 R^(b) groups.

For example, in certain embodiments, R^(a) can be selected from thegroup consisting of a linear C₅₋₄₀ alkyl group, a branched C₅₋₄₀ alkylgroup, a linear C₅₋₄₀ alkoxy group, a branched C₅₋₄₀ alkoxy group, alinear C₅₋₄₀ alkylthio group, and a branched C₅₋₄₀ alkylthio group.Accordingly, using benzodithiophene as the representative donor subunit,D can be selected from the group consisting of:

where R^(b), at each occurrence, can be a linear or branched C₅₋₄₀ alkylgroup.

In other embodiments, each R^(a) can be -L′-Ar′ or -L′-Ar′-Ar′, where L′and Ar′ are as defined herein. For example, each Ar′ can be a thienylgroup or a thienyl-fused polycyclic group, each of which can beoptionally substituted as described herein. To illustrate, the bridgeddithiophene moiety can be functionalized with a thienyl group, abithienyl group, or a thienyl-fused polycyclic group, each of which canbe optionally substituted as described herein. To illustrate further,and using benzodithiophene again as the representative donor subunit, Dcan be selected from the group consisting of:

can be selected from the group consisting of:

each of which can be optionally substituted with 1-2 R^(b) groups, andR^(b), at each occurrence, independently can be a C₃₋₄₀ alkyl group.

In further embodiments, the donor subunit (D) can have a formulaselected from

wherein:Ar¹ and Ar² independently are an optionally substituted C₆₋₁₄ aryl groupor an optionally substituted 5-14 membered heteroaryl group;Ar³ and Ar⁴ independently are an optionally substituted phenyl group oran optionally substituted 5- or 6-membered heteroaryl group;L, at each occurrence, independently is selected from —O—, —S—, —Se—,—OC(O)—, —C(O)O—, a divalent C₁₋₂₀ alkyl group, a divalent C₁₋₂₀haloalkyl group, and a covalent bond;L¹, at each occurrence, independently is selected from —O—, —S—, —Se—,—OC(O)—, —C(O)O—, a divalent C₁₋₂₀ alkyl group, and a divalent C₁₋₂₀haloalkyl group;U and U′ independently are selected from —O—, —S—, and —Se—;V and V′ independently are —CR═ or —N═;W, at each occurrence, independently is selected from —O—, —S—, and—Se—;W′, at each occurrence, independently is —CR═ or —N═; andR, at each occurrence, independently is selected from H, a halogen, —CN,and L′R′, wherein L′, at each occurrence, is selected from —O—, —S—,—Se—, —C(O)—, —OC(O)—, —C(O)O—, and a covalent bond; and R′, at eachoccurrence, independently is selected from a C₁₋₄₀ alkyl group, a C₂₋₄₀alkenyl group, a C₂₋₄₀ alkynyl group, and a C₁₋₄₀ haloalkyl group.

In certain embodiments, each of U, U′ and W can be —S—, and each of V,V′ and W′ can be —CH═ or —CCl═, thus providing a it group having aformula selected from:

wherein Ar¹, Ar², Ar³, Ar⁴, L and L¹ are as defined herein. Toillustrate, L and L¹ can be selected from —O—, —S—, —OC(O)—, —C(O)O—, adivalent C₁₋₂₀ alkyl group, and a covalent bond.

In certain embodiments, the donor subunit (D) can include a chlorinatedbridged-dithiophene unit. Examples of chlorinated bridged-dithiopheneunit include:

wherein R^(b), at each occurrence, independently can be a C₃₋₄₀ alkylgroup.

In some embodiments, the donor subunit (D) can include one or morethienyl groups optionally substituted with 1-2 alkoxy groups.

The acceptor subunit (A) includes an electron-poor conjugated moiety(δ). In certain embodiments, the electron-poor conjugated moiety can bean 8-14 membered polycyclic heteroaryl moiety including either at leastone ring that has two or more heteroatoms selected from N and S, and/orat least one ring that is substituted with one or moreelectron-withdrawing groups such as F, Cl, an oxo group, a carbonylgroup, a carboxylic ester group, or a sulfonyl group. In particularembodiments, the electron-poor conjugated moiety can be flanked byoptionally substituted thienyl or thieno[3,2-b]thiophenyl groups. Incertain embodiments, the electron-poor conjugated moiety (δ) can includeone or more chlorinated thienyl groups.

Accordingly, in various embodiments, the acceptor subunit (A) can berepresented by the formula:

where δ represents the electron-poor conjugated moiety, and R^(c), ateach occurrence, can be H or R, where R, at each occurrence,independently can be selected from the group consisting of a C₆₋₂₀ alkylgroup, a C₆₋₂₀ alkenyl group, and a C₆₋₂₀ haloalkyl group.

Examples of electron-poor conjugated moieties (δ) include, but are notlimited to:

where R^(d), at each occurrence, independently can be selected from aC₃₋₄₀ alkyl group, a C₃₋₄₀ alkenyl group, and a C₃₋₄₀ haloalkyl group;and R^(f), at each occurrence, independently can be selected from thegroup consisting of H, F, Cl, —CN, —S(O)₂—C₁₋₂₀ alkyl, —C(O)—OC₁₋₂₀alkyl, —C(O)—C₁₋₂₀ alkyl, a C₁₋₂₀ alkyl group, a C₂₋₂₀ alkenyl group, aC₁₋₂₀ alkoxy group, a C₁₋₂₀ alkylthio group, and a C₁₋₂₀ haloalkylgroup. For example, R^(d), at each occurrence, independently can be alinear or branched C₆₋₂₀ alkyl group; and R^(f), at each occurrence,independently can be selected from H, F, Cl, C(O)R^(e), C(O)OR^(e), andS(O)₂R^(e); where R^(e), at each occurrence, independently can be alinear or branched C₆₋₂₀ alkyl group.

Accordingly, in some embodiments, the electron donor polymer can be analternating copolymer having the formula 10, 11, or 12:

wherein:R^(a), at each occurrence, can be selected from the group consisting of-L′-R^(b), -L′-Ar′, and -L′-Ar′-Ar′, where L′ is selected from the groupconsisting of —O—, —S—, and a covalent bond; R^(b) is selected from thegroup consisting of a C₃₋₄₀ alkyl group, a C₃₋₄₀ alkenyl group, and aC₃₋₄₀ haloalkyl group; and Ar′, at each occurrence, independently is a5-14 membered heteroaryl group optionally substituted with 1-2 R^(b)groups;R^(c), at each occurrence, is H or R, where R, at each occurrence,independently is selected from the group consisting of a C₆₋₂₀ alkylgroup, a C₆₋₂₀ alkenyl group, and a C₆₋₂₀ haloalkyl group;δ is selected from the group consisting of:

where R^(d), at each occurrence, independently can be selected from aC₃₋₄₀ alkyl group, a C₃₋₄₀ alkenyl group, and a C₃₋₄₀ haloalkyl group;and R^(f), at each occurrence, independently can be selected from thegroup consisting of H, F, Cl, —CN, —S(O)₂—C₁₋₂₀ alkyl, —C(O)—OC₁₋₂₀alkyl, —C(O)—C₁₋₂₀ alkyl, a C₁₋₂₀ alkyl group, a C₂₋₂₀ alkenyl group, aC₁₋₂₀ alkoxy group, a C₁₋₂₀ alkylthio group, and a C₁₋₂₀ haloalkylgroup. For example, R^(d), at each occurrence, independently can be alinear or branched C₆₋₂₀ alkyl group; and R^(f), at each occurrence,independently can be selected from H, F, Cl, C(O)R^(e), C(O)OR^(e), andS(O)₂R^(e); where R^(e), at each occurrence, independently can be alinear or branched C₆₋₂₀ alkyl group; andn is an integer in the range of 2 to 5,000.

In other embodiments, the electron donor polymer can be a randomcopolymer having the formula 13 or 14:

wherein:R^(a), at each occurrence, can be selected from the group consisting of-L′-R^(b), -L′-Ar′, and -L′-Ar′-Ar′, where L′ is selected from the groupconsisting of —O—, —S—, and a covalent bond; R^(b) is selected from thegroup consisting of a C₃₋₄₀ alkyl group, a C₃₋₄₀ alkenyl group, and aC₃₋₄₀ haloalkyl group; and Ar′, at each occurrence, independently is a5-14 membered heteroaryl group optionally substituted with 1-2 R^(b)groups;R, at each occurrence, independently can be a C₆₋₂₀ alkyl group;δ, at each occurrence, independently can be selected from the groupconsisting of:

where R^(d), at each occurrence, independently can be selected from aC₃₋₄₀ alkyl group, a C₃₋₄₀ alkenyl group, and a C₃₋₄₀ haloalkyl group;and R^(f), at each occurrence, independently can be selected from thegroup consisting of H, F, Cl, —CN, —S(O)₂—C₁₋₂₀ alkyl, —C(O)—OC₁₋₂₀alkyl, —C(O)—C₁₋₂₀alkyl, a C₁₋₂₀ alkyl group, a C₂₋₂₀ alkenyl group, aC₁₋₂₀ alkoxy group, a C₁₋₂₀ alkylthio group, and a C₁₋₂₀ haloalkylgroup. For example, R^(d), at each occurrence, independently can be alinear or branched C₆₋₂₀ alkyl group; and R^(f), at each occurrence,independently can be selected from H, F, Cl, C(O)R^(e), C(O)OR^(e), andS(O)₂R^(e); where R^(e), at each occurrence, independently can be alinear or branched C₆₋₂₀ alkyl group;x and y independently are a real number, wherein 0.1≦x≦0.9, 0.1≦y≦0.9,and the sum of x and y is about 1; andn is an integer in the range of 2 to 5,000.

Accordingly, the present polymer-polymer blend can include an electronacceptor polymer according to any of formula 1-8 and an electron donorpolymer according to any of formula 10-14. In certain preferredembodiments, the present polymer-polymer blend can include an electronacceptor polymer according to formula 5-8 and an electron donor polymerthat is an alternating copolymer of a formula selected from the groupconsisting of:

where R^(b), at each occurrence, can be a linear or branched C₃₋₄₀ alkylgroup; R^(c), at each occurrence, can be H or a C₆₋₂₀ alkyl group; and ncan be an integer in the range of 5 to 5,000.

In other preferred embodiments, the present polymer-polymer blend caninclude an electron acceptor polymer according to any of formula 5-8 andan electron donor polymer that is a random copolymer of a formulaselected from the group consisting of:

where R^(b), at each occurrence, can be a linear or branched C₃₋₄₀ alkylgroup; R, at each occurrence, can be a C₆₋₂₀ alkyl group; x and yindependently are a real number, wherein 0.1≦x≦0.9, 0.1≦y≦0.9(0.2≦x≦0.8, 0.2≦y≦0.8), and the sum of x and y is about 1; and n can bean integer in the range of 5 to 5,000.

In certain preferred embodiments, the present polymer-polymer blend caninclude an electron acceptor polymer according to any of formula 5-8 andan electron donor polymer that is an alternating copolymer of a formulaselected from the group consisting of:

where R^(b), R^(d), R^(e), at each occurrence, independently can be alinear or branched C₃₋₄₀ alkyl group; R^(c), at each occurrence, can beH or a C₆₋₂₀ alkyl group; R^(f), at each occurrence, independently canbe selected from H, F, Cl, C(O)R^(e), C(O)OR^(e), and S(O)₂R^(e); whereR^(e), at each occurrence, independently can be a linear or branchedC₆₋₂₀ alkyl group; r can be 0 or 1; and n can be an integer in the rangeof 5 to 5,000. In certain embodiments, the electron donor polymer can bea random copolymer having two repeat units of any of formula 43-56. Forexample, the electron donor polymer can be a random copolymer having tworepeat units of formula 43, where in one repeat unit, r is 1 and R^(c)is H, and in the other repeat unit r is 1 and R^(c) is a C₆₋₂₀ alkylgroup.

Illustrative examples of embodiments where the electron donor polymerincludes a naphthodithiophene moiety as the donor subunit can include:

where R^(b), R^(d), R^(f), R, x, y, and n are as defined herein.

Illustrative examples of embodiments where the electron donor polymerincludes one or more chlorinated groups can include:

where R^(a) can be -L′-Ar′ or -L′-Ar′-Ar′, where L′ is selected from thegroup consisting of —O—, —S—, —C(O)O—, —OC(O)—, and a covalent bond;each Ar′ can be a thienyl group or a thienyl-fused polycyclic group,each of which can be optionally substituted as described herein; R^(b),at each occurrence, can be a linear or branched C₃₋₄₀ alkyl group; R, ateach occurrence, can be a C₆₋₂₀ alkyl group; x and y independently are areal number, wherein 0.1≦x≦0.9, 0.1≦y≦0.9 (0.2≦x≦0.8, 0.2≦y≦0.8), andthe sum of x and y is about 1; and n can be an integer in the range of 5to 5,000.

Electron-donor polymers and electron-acceptor polymers according to thepresent teachings and monomers leading to them can be prepared accordingto procedures analogous to those described in the Examples. Inparticular, Stille coupling or Suzuki coupling reactions can be used toprepare co-polymeric compounds according to the present teachings withhigh molecular weights and in high yields (≧75%) and purity, asconfirmed by ¹H NMR spectra, elemental analysis, and/or GPCmeasurements. Alternatively, the present polymers can be prepared fromcommercially available starting materials, compounds known in theliterature, or via other readily prepared intermediates, by employingstandard synthetic methods and procedures known to those skilled in theart. Standard synthetic methods and procedures for the preparation oforganic molecules and functional group transformations and manipulationscan be readily obtained from the relevant scientific literature or fromstandard textbooks in the field.

The electron-donor polymers and electron-acceptor polymers in thepresent polymer-polymer blends can be soluble in various common organicsolvents. As used herein, a polymer can be considered soluble in asolvent when at least 0.1 mg of the polymer can be dissolved in 1 mL ofthe solvent. Examples of common organic solvents include petroleumethers; acetonitrile; aromatic hydrocarbons such as benzene, toluene,xylene, and mesitylene; ketones such as acetone, and methyl ethylketone; ethers such as tetrahydrofuran, dioxane,bis(2-methoxyethyl)ether, diethyl ether, di-isopropyl ether, and t-butylmethyl ether; alcohols such as methanol, ethanol, butanol, and isopropylalcohol; aliphatic hydrocarbons such as hexanes; esters such as methylacetate, ethyl acetate, methyl formate, ethyl formate, isopropylacetate, and butyl acetate; amides such as dimethylformamide anddimethylacetamide; sulfoxides such as dimethylsulfoxide; halogenatedaliphatic and aromatic hydrocarbons such as dichloromethane, chloroform,ethylene chloride, chlorobenzene, dichlorobenzene, and trichlorobenzene;and cyclic solvents such as cyclopentanone, cyclohexanone, and2-methypyrrolidone. In preferred embodiments, the solvent can beselected from the group consisting of chlorobenzene, dichlorobenzene(o-dichlorobenzene, m-dichlorobenzene, p-dichlorobenzene, or mixturesthereof), trichlorobenzene, benzene, toluene, chloroform,dichloromethane, dichloroethane, xylenes, α,α,α-trichlorotoluene, methylnaphthalene (e.g., 1-methylnaphthalene, 2-methylnaphthalene, or mixturesthereof), chloronaphthalene (e.g., 1-chloronaphthalene,2-chloronaphthalene, or mixtures thereof), and mixtures thereof.

The electron-donor polymers and electron-acceptor polymers describedherein can be dissolved, dispersed or suspended in a single solvent ormixture of solvents to provide a blend composition suitable for solutionprocessing techniques. Common solution processing techniques include,for example, spin coating, slot coating, doctor blading, drop-casting,zone casting, dip coating, blade coating, or spraying. Another exampleof solution processing technique is printing. As used herein, “printing”includes a noncontact process such as inkjet printing, microdispensingand the like, and a contact process such as screen-printing, gravureprinting, offset printing, flexographic printing, lithographic printing,pad printing, microcontact printing and the like.

An organic photoactive semiconductor component can be prepared as ablended film deposited from a solution or dispersion containing apolymer-polymer blend according to the present teachings. For example,an all-polymer blend according to the present teachings can be dissolvedin chloroform, chlorobenzene, or a mixture thereof, where theelectron-donor and electron-acceptor polymers together can be present inthe solution from about 0.5 wt % to about 10 wt %, preferably, fromabout 0.8 wt % to about 5 wt %, and more preferably, from about 1 wt %to about 3 wt %. The weight ratio of the electron-donor polymers to theelectron-acceptor polymers in the blend can be from about 20:1 to about1:20, for example, from about 10:1 to about 1:10, preferably from about5:1 to about 1:5, from about 3:1 to about 1:3, from about 2: to about1:2, and more preferably about 1:1. The photoactive layer also cancontain a polymeric binder, which can be present from about 5 to about95% by weight. The polymeric binder, for example, can be asemicrystalline polymer selected from polystyrene (PS), high densitypolyethylene (HDPE), polypropylene (PP) and polymethylmethacrylate(PMMA). In some embodiments, the polymeric blend can be used togetherwith additional components that are optically active, for example,components that can assist in light harvesting by capturing andtransferring excitons to one or both of the electron-donorpolymers/electron-acceptor polymers in the blend, and/or opticallynon-active components to modify and/or improve processing and/or deviceperformance. Such optically non-active components can includealkanethiols (e.g., alkanedithiols) and other α,ω-functionalized alkanes(e.g., diiodoalkanes) as known in the art. See e.g., U.S. Pat. No.8,227,691.

An organic semiconductor film can be prepared from a polymeric blendaccording to the present teachings in any form that provides forseparation of electron-hole pairs. In some embodiments, the organicsemiconductor film can be in a planar bilayer form. In otherembodiments, the organic semiconductor film can be in a bilayer formwith a diffuse interface. In preferred embodiments, the organicsemiconductor film can be a single layer in a bulk heterojunction (BHJ)form. As used herein, a “film” means a continuous piece of a substancehaving a high length to thickness ratio and a high width to thicknessratio.

An organic semiconductor film prepared from an all-polymer blendaccording to the present teachings can be photoactive because theelectron-donor polymers and/or the electron-acceptor polymers thereinare capable of absorbing photons to generate excitons for the generationof a photocurrent. Accordingly, the present all-polymer blend can beused to prepare a photoactive component in an optoelectronic device,where the photoactive component or layer can be fabricated by firstpreparing a blend composition (e.g., a solution or dispersion) thatincludes an electron-donor polymer and an electron-acceptor polymerdisclosed herein dissolved or dispersed in a liquid medium such as asolvent or a mixture of solvents, depositing the blend composition on asubstrate (e.g., an electrode-substrate) preferably via a solution-phaseprocess, and removing the solvent or mixture of solvents to provide thephotoactive layer. By having the blend composition provided as anintimate mixture of the electron-donor polymers and theelectron-acceptor polymers, bulk heterojunctions can be created uponremoval of the solvent (optionally under reduced pressure and/orelevated temperature), during which nanoscale phase separation of theelectron-donor polymers and the electron-acceptor polymers takes place.In some embodiments, the depositing step can be carried out by printing,including inkjet printing and various contact printing techniques (e.g.,screen-printing, gravure printing, offset printing, pad printing,lithographic printing, flexographic printing, and microcontactprinting). In other embodiments, the depositing step can be carried outby spin coating, slot-die coating, drop-casting, zone casting, dipcoating, blade coating, or spraying. When the film is formed by spincoating, the spin speed can range from about 300 rpm to about 6000 rpm,or from about 500 rpm to about 2000 rpm. Subsequent processing steps caninclude thermal annealing or irradiation of the deposited film. Forexample, the blended film can be annealed from about 50° C. to about300° C., preferably from about 70° C. to about 200° C., more preferablyfrom about 90° C. to about 180° C. for about 1 min to about 20 minutes.The annealing step can be carried out under an inert atmosphere (e.g.,under nitrogen). Irradiation of the deposited film can be carried outusing infrared light or ultraviolet light. As used herein, “annealing”refers to a post-deposition heat treatment to the semicrystallinepolymer film in ambient or under reduced/increased pressure for a timeduration of more than 60 seconds, and “annealing temperature” refers tothe maximum temperature that the polymer film is exposed to for at least30 seconds during this process of annealing. Without wishing to be boundby any particular theory, it is believed that annealing can result inimproved PCEs of the all-polymer blend. Furthermore, an advantage of thepresent all-polymer blend can include improved stability during theannealing step compared to known polymer:fullerene blends. Thephotoactive layer typically can have a thickness ranging from about 30nm to about 500 nm. In preferred embodiments, the photoactive layer canbe a thin film having a thickness of about 80-300 nm.

Optoelectronic devices that can incorporate a photoactive layer preparedfrom an all-polymer blend according to the present teachings include,but are not limited to, photovoltaic/solar cells, photodetectors (orphotodiodes), light-emitting diodes, and light-emitting transistors. Thepresent polymeric blends can offer processing and operation advantagesin the fabrication and/or the use of these devices.

For example, articles of manufacture such as the various devicesdescribed herein can be an optoelectronic device including a firstelectrode, a second electrode, and a photoactive component disposedbetween the first electrode and the second electrode, where thephotoactive component includes a polymeric blend of the presentteachings.

In various embodiments, the optoelectronic device can be configured as asolar cell, in particular, a bulk-heterojunction solar cell. FIG. 1illustrates a representative structure of a bulk-heterojunction organicsolar cell which can incorporate a polymeric blend according to thepresent teachings. As shown, a representative solar cell generallyincludes a substrate 20, an anode 22, a cathode 26, and a photoactivelayer 24 between the anode and the cathode. In some embodiments, one ormore optional interlayers can be present between the anode and thephotoactive layer and/or between the cathode and the photoactive layer.

The substrate can be a solid, rigid or flexible layer designed toprovide robustness to the device. In preferred embodiments, thesubstrate can be transparent or semi-transparent in the spectral regionof interest. As used herein, a material is considered “transparent” whenit has transmittance over 50%, and a material is considered“semi-transparent” when it has transmittance between about 50% and about5%. The substrate can comprise any suitable material known in the artsuch as glass or a flexible plastic (polymer) film.

The first and second electrodes should have different work functions,with the electrode having the higher work function at or above about 4.5eV (the “high work function electrode”) serving as the hole-injectingelectrode or anode, and the electrode having the lower work function ator below about 4.3 eV (the “low work function electrode”) serving as theelectron-injecting electrode. In a traditional OPV device structure, thehigh work function electrode or anode typically is composed of atransparent conducting metal oxide or metal sulfide such as indium tinoxide (ITO), gallium indium tin oxide (GITO), and zinc indium tin oxide(ZITO), or a thin, transparent layer of gold or silver. The low workfunction electrode or cathode typically is composed of a low workfunction metal such as aluminum, indium, calcium, barium, and magnesium.The electrodes can be deposited by thermal vapor deposition, electronbeam evaporation, RF or Magnetron sputtering, chemical vapor depositionor the like.

In various embodiments, the solar cell can include one or more optionalinterface layers (“interlayers”) between the anode and the photoactivelayer and/or between the cathode and the photoactive layer. For example,in some embodiments, an optional smoothing layer (e.g., a film of3,4-polyethylenedioxythiophene (PEDOT), or3,4-polyethylenedioxythiophene:polystyrene-sulfonate (PEDOT:PSS)) can bepresent between the anode and the photoactive layer. The optionalinterlayer(s) can perform other functions such as reducing the energybarrier between the photoactive layer and the electrode, formingselective contacts for a single type of carrier (e.g., a hole-blockinglayer), modifying the work function of the adjacent electrode, and/orprotecting the underlying photoactive layer. In some embodiments, atransition metal oxide layer such as V₂O₅, MoO₃, WO₃ and NiO can bedeposited on top of the ITO anode, instead of using PEDOT or PEDOT:PSSas the p-type buffer. To improve device stability via modification ofthe cathode, an n-type buffer composed of LiF, CsF or similar fluoridescan be provided between the cathode and the photoactive layer. Othern-type buffer materials include TiO_(x), ZnO_(x) and Cs-doped TiO_(x).Depending on the composition, the interlayers can be solution-processed(e.g., sol-gel deposition, self-assembled monolayers) or deposited byvacuum processes such as thermal evaporation or sputtering.

In certain embodiments, a solar cell according to the present teachingscan include a transparent glass substrate onto which an electrode layer(anode) made of indium tin oxide (ITO) is applied. This electrode layercan have a relatively rough surface, and a smoothing layer made of apolymer, typically PEDOT:PSS made electrically conductive throughdoping, can be applied on top of the electrode layer to enhance itssurface morphology. Other similar interlayers can be optionally presentbetween the anode and the photoactive layer for improving mechanical,chemical, and/or electronic properties of the device. The photoactivelayer is composed of an all-polymer blend as described above, and canhave a layer thickness of, e.g., about 80 nm to a few μm. Before acounter electrode (cathode) is applied, an electrically insulatingtransition layer can be applied onto the photoactive layer. Thistransition layer can be made of an alkali halide, e.g., LiF, and can bevapor-deposited in vacuum. Again, similar to the anode, other similarinterlayers can be optionally present between the photoactive layer andthe cathode for improving mechanical, chemical, and/or electronicproperties of the device.

In certain embodiments, a solar cell according to the present teachingscan have an inverted device structure, where a modified ITO film is usedas the cathode. For example, the ITO can be modified by n-type metaloxides or metal carbonates such as TiO_(x), ZnO_(x), Cs-doped TiO_(x),and caesium carbonate. In particular embodiments, the inverted OPV caninclude a solution-processed ZnO_(x) n-type interface layer as describedin Lloyd et al., “Influence of the hole-transport layer on the initialbehavior and lifetime of inverted organic photovoltaics,” Solar EnergyMaterials and Solar Cells, 95(5): 1382-1388 (2011). Compared with thetraditional device structure, inverted-type devices can demonstratebetter long-term ambient stability by avoiding the need for thecorrosive and hygroscopic hole-transporting PEDOT:PSS and low workfunction metal cathode. The anode of an inverted OPV cell can becomposed of Ag, Au, and the like, with an optional p-type interfacelayer composed of transition metal oxides such as V₂O₅, MoO₃, WO₃ andNiO.

EXAMPLES

The following examples are provided to illustrate further and tofacilitate the understanding of the present teachings and are not in anyway intended to limit the invention.

All reagents were purchased from commercial sources and used withoutfurther purification unless otherwise noted. Characterization data areprovided in some cases by ¹H-NMR, ¹³C-NMR, and/or elemental analysis.NMR spectra were recorded on an Inova 500 NMR spectrometer (¹H, 500MHz). Elemental analyses were performed by Midwest Microlab, LLC.

Preparation of Electron-Acceptor Polymers Example 1 Preparation of poly{[N,N′-bis(2-ethylhexyl)-1,4,5,8-naphthalenediimide-2,6-diyl]-alt-5,5′-(2,2′-bithiophene)} [P(NDI2EH-T2)]

Preparation of 2,6-dibromonaphthalene-1,4,5,8-tetracarboxydianhydride(NDA-Br₂): A mixture of 1,4,5,8-naphthalenetetracarboxylic dianhydride(2.8 g, 10.3 mmol) and oleum (20% SO₃, 100 mL) was stirred at 55° C. for2 hours. To this mixture, a solution of dibromoisocyanuric acid (3.0 g,10.5 mmol) in oleum (50 mL) was added over 40 minutes. The resultingmixture was then warmed to 85° C. and maintained at this temperature for43 hours. After cooling to room temperature, the reaction mixture waspoured onto crushed ice (420 g), diluted with water (400 mL), and thenstirred at room temperature for 1 hour. The resulting precipitates werecollected by centrifugation, washed with water and methanol, collectedby centrifugation and finally dried under vacuum, leading to a greenishyellow solid (3.6 g, 8.5 mmol, yield 82.2%). Elemental Analysis (calc.C, 39.47; H, 0.47; N, 0.00). found C, 38.20; H, 0.79; N, 0.00.

Preparation ofN,N′-bis(2-ethylhexyl)-2,6-dibromonaphthalene-1,4,5,8-bis(dicarboximide)(NDI2EH-Br₂): A mixture of NDA-Br₂ (above, 1.6 g, 3.9 mmol),2-ethylhexylamine (1.4 mL, 8.5 mmol), o-xylene (6 mL), and propionicacid (2 mL) was stirred at 140° C. for 1 hour. After cooling to roomtemperature, methanol (10 mL) was added to the reaction mixture and theresulting precipitate was collected by filtration, washed with methanol,and dried in vacuum leading to the crude product as a red solid (0.81g). Further purification was carried out by column chromatography onsilica gel using a mixture of chloroform:hexane (5:1, v/v) as eluent,affording a slightly yellow solid as the product (0.61 g, 0.94 mmol,yield 24.4%). ¹H NMR (CDCl₃, 500 MHz): δ 9.01 (s, 2H), 4.10-4.25 (m,4H), 19.4-1.97 (m, 2H), 1.20-1.40 (m, 16H), 0.87-1.03 (m, 12H). ¹³C NMR(CDCl₃, 125 MHz): δ 161.4, 161.2, 139.4, 128.6, 127.9, 125.5, 124.3,45.3, 38.0, 30.8, 28.7, 24.2, 23.3, 14.3, 10.8.

Preparation of P(NDI2EH-T2): Under argon, a mixture of NDI2EH-Br₂(above, 98 mg, 0.15 mmol), 5,5′-bis(trimethylstannyl)-2,2′-bithiophene(74 mg, 0.15 mmol), and Pd(PPh₃)₂Cl₂ (3.5 mg, 0.005 mmol) in anhydroustoluene (5 mL) was stirred at 90° C. for 4 days. Bromobenzene (0.3 mL)was then added to the reaction and the resulting mixture was stirred foran additional 12 hours. After cooling to room temperature, a solution ofpotassium fluoride (1.2 g) in water (2.5 mL) was added. This mixture wasstirred at room temperature for 2 hours and the precipitate wascollected by filtration. The solid was taken with a small amount ofchloroform, methanol was added, and the solid collected by filtration.This procedure was repeated using chloroform and acetone, leading to adeep blue solid as the crude product. This crude product was purified bySoxhlet extraction with acetone for 24 hours (80 mg, yield 80.7%). ¹HNMR (CDCl₃, 500 MHz): δ 8.82 (br, 2H), 7.35 (br, 4H), 4.15 (br, 4H),1.97 (br, 2H), 1.18-1.70 (m, br, 16H). 0.80-1.12 (m, br, 12H). ElementalAnalysis (calc. C, 69.91; H, 6.18; N, 4.29). found C, 69.63; H, 5.66; N,3.71.

Example 2 Preparation ofpoly{[N,N′-bis(2-ethylhexyl)-1,4,5,8-naphthalenediimide-2,6-diyl]-alt-2,5-thiophene} [P(NDI2EH-T1)]

Preparation of P(NDI2EH-T1): Under argon, a mixture of NDI2EH-Br₂(Example 1, 84 mg, 0.13 mmol), 2,5-bis(trimethylstannyl)thiophene (53mg, 0.13 mmol), and Pd(PPh₃)₂Cl₂ (3.0 mg, 0.004 mmol) in anhydroustoluene (5 mL) was stirred at 90° C. for 4 days. Bromobenzene (0.3 mL)was then added and the resulting mixture was stirred at 90° C. for anadditional 12 hours. Upon cooling to room temperature, a solution ofpotassium fluoride (1.2 g) in water (2.5 mL) was added. This mixture wasstirred at room temperature for 2 hours and the precipitate collected byfiltration. The solid was taken with a small amount of chloroform,methanol was added, and the resulting solid collected by filtration.This procedure was repeated using chloroform and acetone, leading to adeep blue solid as the crude product (20.0 mg, yield 20.7%). ElementalAnalysis (calc. C, 71.55; H, 6.71; N, 4.91). found C, 71.59; H, 6.00; N,4.56.

Example 3 Preparation ofPoly{[N,N′-bis(2-octyldodecyl)-1,4,5,8-naphthalenediimide-2,6-diyl]-alt-5,5′-(2,2′-bithiophene)} [P(NDI2OD-T2)]

Preparation of 1-iodo-2-octyldodecane: Iodine (12.25 g, 48.3 mmol) wasadded to a solution of 2-octyl-1-dodecanol (12.42 g, 41.6 mmol),triphenylphosphine (13.17 g, 50.2 mmol), and imidazole (3.42 g, 50.2mmol) in 80 mL dichloromethane at 0° C. After stirring for 30 minutes,the reaction mixture was allowed to warm to room temperature over 4hours before 12 mL of saturated Na₂SO₃ (aq) was added. The organics wereconcentrated by evaporation and the mixture taken up in 500 mL pentane,washed three times with 200 mL water, and once with 150 mL brine. Themixture was then passed through a 3 cm silica gel plug, and dried overNa₂SO₄. The organics were concentrated by evaporation to give acolorless oil (15.78 g, yield 92.9%). ¹H NMR (CDCl₃ 500 MHz): δ: 2.60(d, J=5.0 Hz, 2H), 2.00 (t, J=5.0 Hz, 1H), 1.30-1.20 (b, 32H), 0.89 (t,J=7.5 Hz, 6H); MS (EI): m/z (%) 408.23 (100) [M⁺]. Elemental Analysis(calc. C, 58.81; H, 10.12). found C, 58.70; H, 9.97.

Preparation of 2-octyldodecylamine: 1-Iodo-2-octyldodecane (5.90 g, 14.5mmol) and potassium phthalimide (2.94 g, 15.9 mmol) were dissolved in 25mL of DMF and vigorously stirred for 72 h at 25° C. The reaction mixturewas poured into 200 mL of pentane, and washed four times with 100 mLwater. The mixture was then passed through a 3 cm silica gel plug, andconcentrated to give a colorless oil. The oil was next dissolved in 150mL of ethanol, and 4 mL of hydrazine hydrate were added, leading to amixture which was heated to reflux overnight. The resulting precipitateswere collected by filtration, dissolved in 100 mL water, and thesolution was made alkaline by addition of 6 M NaOH (aq). The resultingmixture was dissolved in 200 mL pentane, washed four times with 100 mLof water, once with 70 mL of brine, dried over MgSO₄, and concentratedto give a colorless oil (3.08 g, 72% yield). ¹H NMR (CDCl₃ 500 MHz): δ:2.60 (d, J=5.0 Hz, 2H), 2.00 (t, J=5.0 Hz, 1H), 1.30-1.20 (b, 32H), 0.89(t, J=7.5 Hz, 6H); MS (EI): m/z (%) 297.34 (100) [M⁺]. ElementalAnalysis (calc. C, 80.73; H, 14.57). found C, 80.78; H, 14.52.

Preparation ofN,N′-bis(2-octyldodecyl)-2,6-dibromonaphthalene-1,4,5,8-bis(dicarboximide)(NDI2OD-Br₂): A mixture of NDA-Br₂ (Example 1, 2.34 g, 5.49 mmol),2-octyldodecylamine (4.10 g, 13.78 mmol), o-xylene (18 mL), andpropionic acid (6 mL) was stirred at 140° C. for 1 hour. Upon cooling toroom temperature, most of the solvent was removed in vacuo, and theresidue was purified by a column chromatography on silica gel with amixture of chloroform:hexane (1:1, v/v) as the eluent, affording aslightly yellow solid as the product (1.98 g, 2.01 mmol, yield 36.7%).¹H NMR (CDCl₃ 500 MHz): δ: 8.95 (s, 2H), 4.12 (d, J=7.5 Hz, 4H), 1.97(m, 2H), 1.20-1.40 (m, 64H), 0.84-0.89 (m, 12H). ¹³C NMR (CDCl₃, 125MHz): δ: 161.3, 161.1, 139.3, 128.5, 127.8, 125.4, 124.2, 45.6, 36.6,32.1, 32.0, 31.7, 30.2, 29.9, 29.8, 29.7, 29.6, 29.5, 26.5, 22.9, 22.8,14.3. Elemental Analysis (calc. C, 65.84; H, 8.60; N, 2.84). found C,65.68; H, 8.60; N, 2.89.

Preparation of P(NDI2OD-T2): Under argon, a mixture of NDI-2OD-Br₂ (95mg, 0.096 mmol), 5,5′-bis(trimethylstannyl)-2,2′-bithiophene (48 mg,0.096 mmol), and Pd(PPh₃)₂Cl₂ (3.5 mg, 0.005 mmol) in anhydrous toluene(5 mL) was stirred at 90° C. for 4 days. Bromobenzene (0.2 mL) was thenadded and the reaction mixture was maintained at 90° C. for anadditional 12 hours. Upon cooling to room temperature, a solution ofpotassium fluoride (1 g) in water (2 mL) was added. This mixture wasstirred at room temperature for 2 hours before it was extracted withchloroform (60 mL×2). Organic layers were combined, washed with water(50 mL×2), dried over anhydrous sodium sulfate, and concentrated on arotary evaporator. The residue was taken with a small amount ofchloroform and precipitated in methanol and acetone in sequence. Theobtained blue solid product was purified by Soxhlet extraction withacetone for 48 hours. The remaining solid residue was redissolved inchloroform (50 mL) and the resulting mixture was heated to boil. Uponcooling to room temperature, the chloroform solution was filteredthrough a 5 μm filter, and the filtrate was added slowly to methanol (50mL). The precipitates were collected by filtration, washed withmethanol, and dried in vacuum, leading to a deep blue solid as theproduct (88.0 mg, yield 92.1%). ¹H NMR (CDCl₃ 500 MHz): δ: 8.53-8.84 (m,br, 2H), 7.20-7.48 (br, 4H), 4.13 (s, br, 2H), 2.00 (s, br, 4H),1.05-1.30 (s, br, 64H), 0.87 (s, br, 12H). GPC: M_(n)=47.8K Da,M_(w)=264.4K Da, PDI=5.53. Elemental Analysis (calc. C, 75.26; H, 8.96;N, 2.83, Br, 0.00). found C, 75.22; H, 9.01; N, 2.77, Br, 0.00.

Example 4 Preparation ofPoly{[N,N′-bis(1-methylhexyl)-1,4,5,8-naphthalenediimide-2,6-diyl]-alt-5,5′-(2,2′-bithiophene)} [P(NDI1 MH-T2)]

Preparation ofN,N′-bis(1-methylhexyl)-2,6-dibromonaphthalene-1,4,5,8-bis(dicarboximide)(NDI1 MH-Br₂): A mixture of NDA-Br₂ (Example 1, 2.42 g, 5.68 mmol),1-methylhexylamine (2.5 mL, 16.55 mmol), propionic acid (12 mL), ando-xylene (36 mL) was stirred under argon at 140° C. for 17 hours. Uponcooling to room temperature, solvents were removed in vacuo and theresidue was subject to a column chromatography on silica gel using amixture of CHCl₃:hexane (1:1, v/v) as the eluent, leading to slightlyyellow solid as the product (0.24 g, 0.39 mmol, yield 6.9%). ¹H NMR(CDCl₃, 500 MHz): δ 8.96 (s, 2H), 5.24 (m, 2H), 2.13 (m, 2H), 1.94 (m,2H), 1.56 (d, J=7.0 Hz, 6H), 1.10-1.40 (m, 12H), 0.81-0.86 (t, J=7.0 Hz,6H). ¹³C NMR (CDCl₃, 125 MHz): δ: 161.3, 161.3, 139.3, 128.3, 127.8,125.7, 124.5, 51.5, 33.5, 31.8, 26.9, 22.7, 18.3, 14.2.

Preparation of P(NDI1 MH-T2): Under argon, a mixture of NDI1 MH-Br₂(above, 151 mg, 0.24 mmol), 5,5′-bis(trimethylstannyl)-2,2′-bithiophene(120 mg, 0.24 mmol), and Pd(PPh₃)₂Cl₂ (6.5 mg, 0.009 mmol) in anhydroustoluene (12 mL) was stirred at 90° C. for 24 hours. Bromobenzene (0.2mL) was then added and the reaction mixture was maintained at 90° C. foran additional 12 hours. Upon cooling to room temperature, the reactionmixture was added slowly to methanol (50 mL) and the resulting mixturewas stirred at room temperature for 10 minutes. The precipitates werecollected by filtration and washed with methanol. The isolated solid wasthen taken with chloroform (30 mL) and sonicated for 5 minutes. Asolution of potassium fluoride (4 g) in water (8 mL) was added, and thismixture was vigorously stirred at room temperature for 1 hour. Themixture was then diluted with chloroform (100 mL), and washed with water(100 mL×2). The organic layer was concentrated on rotary evaporator. Theresidue was taken with chloroform (30 mL), followed by sonication for 5minutes. This mixture was precipitated in methanol (150 mL), leading todeep blue precipitates, which were collected by filtration, washed withmethanol, and dried in a vacuum (143 mg, yield 94%). Furtherpurification involved Soxhlet extraction with acetone and then anotherprecipitation in methanol. ¹H NMR (CDCl₃, 500 MHz): δ 8.70-8.82 (br,2H), 7.05-7.73 (m, br, 3H), 6.64 (br, 1H), 5.15-5.50 (m, br, 2H),0.71-2.43 (m, br, 28H).

Example 5 Preparation ofpoly{[N,N′-bis(2-octyldodecyl)-1,4,5,8-naphthalenediimide-2,6-diyl]-alt-5,5″′-(quarterthiophene)} [P(NDI2OD-T4)]

Preparation ofN,N′-bis(2-octyldodecyl)-2,6-bis(2-thienyl)naphthalene-1,4,5,8-bis(dicarboximide)(NDI2OD-T1): Under argon, a mixture of NDI2OD-Br₂ (Example 1, 280.0 mg,0.28 mmol), 2-trimethylstannylthiophene (400.0 mg, 1.62 mmol),Pd(PPh₃)₂Cl₂ (28.0 mg, 0.04 mmol) in anhydrous toluene (20 mL) wasstirred at 90° C. for 22 hours. Upon cooling to room temperature, thereaction mixture was diluted with chloroform (100 mL), and the resultingmixture was washed with water (80 mL×2), dried over anhydrous sodiumsulfate (Na₂SO₄), and concentrated on rotary evaporator. The residue wassubject to column chromatography on silica gel with a mixture ofchloroform:hexane (3:2, v/v) as eluent, leading to an orange solid asthe product (240.0 mg, 0.24 mmol, 85.2%). ¹H NMR (CDCl₃ 500 MHz): δ:8.77 (s, 2H), 7.57 (d, J=5.0 Hz, 2H), 7.31 (d, J=3.5 Hz, 2H), 7.21 (m,2H), 4.07 (d, J=7.5 Hz, 4H), 1.95 (m, 2H), 1.18-40 (m, br, 64H),0.84-0.88 (m, 12H); ¹³C NMR (CDCl₃ 125 MHz): δ: 162.8, 162.6, 141.1,140.4, 136.8, 128.4, 128.2, 127.7, 127.6, 125.6, 123.6, 45.0, 36.6,32.1, 31.7. 30.3, 29.9, 29.8, 29.7, 29.6, 29.5, 26.6, 22.9, 14.4, 14.3.

Preparation ofN,N′-bis(2-octyldodecyl)-2,6-bis(5-bromo-2-thienyl)naphthalene-1,4,5,8-bis(dicarboximide)(NDI2OD-BrT1): Under argon, a mixture of NDI2OD-T1 (200.0 mg, 0.20 mmol)and NBS (125.0 mg, 0.70 mmol) in DMF (20 mL) was stirred at 80° C. for25 hours. Upon cooling to room temperature, the reaction mixture waspoured into water (100 mL), and the resulting mixture was extracted withchloroform (100 mL). The organic layer was separated, washed with water(100 mL×2), dried over anhydrous Na₂SO₄, and concentrated on rotaryevaporator. The residue was subject to column chromatography on silicagel with a mixture of chloroform:hexane (2:3, v/v, slowly up to 1:1) aseluent, leading to a red solid as the product (145.0 mg, 0.13 mmol,62.5%). ¹H NMR (CDCl₃, 500 MHz): δ: 8.73 (s, 2H), 7.15 (d, J=4.0 Hz,2H), 7.09 (d, J=4.0, 2H), 4.08 (d, J=7.5 Hz, 4H), 1.93-1.98 (m, 2H),1.20-1.40 (br, m, 64H), 0.83-0.89 (m, 12H). Elemental Analysis (calc. C,64.79; H, 7.72; N, 2.44). found C, 64.50; H, 7.74; N, 2.49.

Preparation of P(NDI2OD-T4): Under argon, a mixture of NDI2OD-BrT1 (92.1mg, 0.08 mmol), 5,5′-bis(trimethylstannyl)-2,2′-bithiophene (39.4 mg,0.08 mmol), and Pd(PPh₃)₂Cl₂ (2.8 mg, 0.004 mmol) in anhydrous toluene(5 mL) was stirred at 90° C. for 4 days. Bromobenzene (0.3 mL) was thenadded and the resulting mixture was stirred for an additional 12 hours.After cooling to room temperature, a solution of potassium fluoride (1g) in water (2 mL) was added. This mixture was stirred and shaken atroom temperature for 1 hour, before it was diluted with chloroform (150mL). The resulting mixture was washed with water (100 mLx3), dried overanhydrous Na₂SO₄, and concentrated on rotary evaporator. The residue wastaken with chloroform (30 mL) and precipitated in methanol (50 mL). Thisprocedure was repeated using chloroform and acetone, leading to a darkblue solid as crude product. This crude product was purified by Soxhletextraction with acetone for 48 hours. The isolated solid was dissolvedin chloroform (50 mL) and then heated to boil. After cooling to roomtemperature, the chloroform solution was passed through a syringe filter(5 μm), and the filtrate was precipitated in methanol (50 mL). Theprecipitates were collected by filtration, washed with methanol, anddried in vacuum, leading to a dark blue solid (87.0 mg, 94.1%). ¹H NMR(CDCl₂CDCl₂, 500 MHz): δ: 8.70-8.81 (m, br, 2H), 7.10-7.40 (m, br, 8H),4.10 (br, 4H), 1.99 (s, br, 2H), 1.10-1.45 (m, br, 64H), 0.86 (m, br,12H). GPC: M_(n)=67.4K Da, M_(w)=170.3K Da, PDI=2.5. Elemental Analysis(calc. C, 72.87; H, 8.04; N, 2.43). found C, 72.69; H, 8.06; N, 2.47.

Example 6 Preparation of Poly{[N,N′-bis(2-octyldodecyl)-1,4,5,8-naphthalenediimide-2,6-diyl]-alt-5,5′-(2,2′-bithiazole)} [P(NDI2OD-TZ2)]

Preparation of P(NDI2OD-TZ2): Under argon, a mixture of NDI2OD-Br₂(Example 1, 235 mg, 0.239 mmol),5,5′-bis(trimethylstannyl)-2,2′-bithiazole (118 mg, 0.239 mmol), andPd(PPh₃)₂Cl₂ (7.0 mg, 0.010 mmol) in anhydrous toluene (12 mL) wasstirred at 90° C. for 3 days. Bromobenzene (0.3 mL) was then added andthe resulting mixture was stirred for an additional 12 hours. Aftercooling to room temperature, a solution of potassium fluoride (2 g) inwater (4 mL) was added. This mixture was stirred and shaken at roomtemperature for 1 hour, before it was diluted with chloroform (150 mL).The resulting mixture was washed with water (100 mL×3), dried overanhydrous Na₂SO₄, and concentrated on a rotary evaporator. The residuewas taken with chloroform (50 mL) and precipitated in methanol (100 mL).This procedure was repeated using chloroform and acetone, leading to adark red solid as the crude product. This crude product was purified bySoxhlet extraction with acetone for 72 hours. The isolated solid wasdissolved in chloroform (80 mL) and then heated to boil. Upon cooling toroom temperature, this chloroform solution was passed through a syringefilter (5 μm), and the filtrate was precipitated in methanol (80 mL).The precipitates were collected by filtration, washed with methanol, anddried in vacuum, leading to a dark red solid (222 mg, 93.7%). ¹H NMR(CDCl₃, 500 MHz): δ: 7.71 (m, br, 2H), 7.54 (m, br, 2H), 4.20-4.25 (m,br, 4H), 1.69 (m, br, 2H), 1.15-1.50 (m, br, 64H) 0.80-0.95 (m, br,12H). Elemental Analysis (calc. C, 72.68; H, 8.74; N, 5.65). found C,72.07; H, 8.61; N, 5.56.

Example 7 Preparation ofPoly{[N,N′-bis(2-octyldodecyl)-1,4,5,8-naphthalenediimide-2,6-diyl]-alt-5,5-(4′,7′-di-2-thienl-2′,1′,3′-benzothiadiazole)}[P(NDI2OD-TBT)]

Preparation of P(NDI2OD-TBT) (Suzuki Coupling Reaction): Under argon, amixture ofN,N′-bis(2-octyldodecyl)-2,6-bis(5′-bromo-2′-thienyl)naphthalene-1,4,5,8-bis(dicarboximide)(NDI2OD-BrT1) (Example 5, 85.0 mg, 0.074 mmol),4,7-bis(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)-2,1,3-benzothiadiazole(28.7 mg, 0.074 mmol), potassium carbonate (81.0 mg, 0.586 mmol), andPd(PPh₃)₄ (1.8 mg, 0.002 mmol) in anhydrous toluene (4 mL) and DMF (2mL) was stirred at 100° C. for 3 days. Bromobenzene (0.3 mL) was thenadded and the resulting mixture was stirred for an additional 12 hours.After cooling to room temperature, the reaction mixture was poured intomethanol (200 mL), and the resulting mixture was stirred at roomtemperature for 15 minutes. The precipitates were collected byfiltration, washed with methanol, and dried in vacuum, leading a darksolid as the product (62.0 mg, 74.6%). Elemental Analysis (calc. C,72.68; H, 8.07; N, 4.99). found C, 72.41; H, 7.90; N, 5.00.

Preparation of P(NDI2OD-TBT) (Stille Coupling Reaction): Under argon, amixture of NDI2OD-Br₂ (Example 1, 84.3 mg, 0.086 mmol),5,5-bis(trimethylstannyl)-4′,7′-di-2-thienyl)-2′,1′,3′-benzothiadiazole(53.6 mg, 0.086 mmol), and Pd(PPh₃)₂Cl₂ (2.5 mg, 0.004 mmol) inanhydrous toluene (6.5 mL) was stirred at 90° C. for 3 days.Bromobenzene (0.3 mL) was then added and the resulting mixture wasstirred for an additional 12 hours. After cooling to room temperature, asolution of potassium fluoride (1 g) in water (2 mL) was added. Thismixture was stirred and shaken at room temperature for 1 hour, before itwas diluted with chloroform (150 mL). The resulting mixture was washedwith water (100 mL×3), dried over anhydrous Na₂SO₄, and concentrated ona rotary evaporator. The residue was taken with chloroform (50 mL) andprecipitated in methanol (100 mL). This procedure was repeated usingchloroform and acetone, leading to a dark solid as the crude product(58.0 mg, 60.3%).

Example 8 Preparation ofPoly{[N,N′-bis(2-hexyldecyl)-1,4,5,8-naphthalenediimide-2,6-diyl]-alt-5,5′-(2,2′-bithiophene)} [P(NDI2HD-T2)]

Preparation of P(NDI2HD-T2): Under argon, a mixture of NDI2OD-Br₂ (1.02g, 1.17 mmol), 5,5′-bis(trimethylstannyl)-2,2′-bithiophene (0.58 g, 1.17mmol), Pd₂ dba₃ (21.4 mg, 0.023 mmol), and P(o-tol)₃ (28.4 mg, 0.093mmol) in anhydrous chlorobenzene (100 mL) was stirred at 90° C. for 18hours. Bromobenzene (2 mL) was then added and the reaction mixture wasmaintained at 90° C. for an additional 14 hours. Upon cooling to roomtemperature, a solution of KF (4 g) in water (8 mL) was added, and theresulting mixture was stirred for 1 h. This reaction mixture was dilutedwith chloroform (300 mL), and the resulting mixture was washed withwater (200 mL×3), dried over anhydrous Na₂SO₄, and concentrated invacuo. The residue was taken with chloroform (250 mL), and precipitatedin methanol (300 mL) and acetone (300 mL) in sequence. The resultingcrude product was then subject to Soxhlet extraction with methanol (15h), acetone (24 h), and hexane (24 h). The isolated solid product wasdissolved in chloroform (600 mL), and this solution was precipitated inmethanol (600 mL). The filtrate was collected by filtration, washed withmethanol, and dried in vacuum, leading to a dark blue solid (1.01 g,98.1%). ¹H NMR (CDCl₂CDCl₂, 500 MHz): δ: 8.50-8.80 (br, 2H), 7.37 (br,4H), 4.13 (br, 4H), 2.00 (br, 2H), 1.20-1.60 (br, m, 48H), 0.87 (br,12H). Elemental Analysis (calc. C, 73.93; H, 8.27; N, 3.19). found C,74.29; H, 8.31; N, 3.37. High temperature GPC: Mn=16.7, Mw=55.4,PDI=3.3.

Example 9 Preparation ofpoly{[N,N′-bis(2-octyldodecyl)-3,4:9,10-perylene diimide-(1,7 &1,6)-diyl]-alt-5,5′-(2,2′-bithiophene} [P(PDI2OD-T2)]

Preparation of N,N′-bis(2-octyldodecyl)-(1,7 & 1,6)-dibromoperylene-3,4:9,10-bis(dicarboxiamide) (PDI2OD-Br₂): A mixture of PDA-Br₂ (0.44 g,0.80 mmol), 2-octyldodecylamine (0.71 g, 2.4 mmol), o-xylene (3 mL), andpropionic acid (1 mL) was stirred at 140° C. for 2 hours. Upon coolingto room temperature, most of the solvents were removed in vacuo, and theresidue was purified by column chromatography on silica gel with amixture of chloroform:hexane (1:1, v/v, slowly up to 2:1) as eluent,affording a red solid as the product (0.63 g, 0.57 mmol, yield 71.5%).¹H NMR (CDCl₃ 500 MHz): δ: 9.51 (d, J=8.0 Hz, 2H), 8.94 (s, 2H), 8.71(d, J=8.0 Hz, 2H), 4.15 (d, J=7.0 Hz, 4H), 2.01 (m, 2H), 1.20-1.50 (m,64H), 0.84-0.89 (m, 12H). Elemental Analysis (calc. C, 69.30; H, 8.00;N, 2.53). found C, 69.42; H, 8.13; N, 2.61.

Preparation of poly{[N,N′-bis(2-octyldodecyl)-3, 4:9,10-perylenediimide-(1,7 & 1,6)-diyl]-alt-5,5′-(2,2′-bithiophene)} [P(PDI2OD-T2)]:Under argon, a mixture of PDI2OD-Br₂ (113.9 mg, 0.103 mmol),5,5′-bis(trimethylstannyl)-2,2′-bithiophene (50.5 mg, 0.103 mmol), andPd(PPh₃)₂Cl₂ (3.1 mg, 0.004 mmol) in anhydrous toluene (6 mL) wasstirred at 90° C. for 2 days. Bromobenzene (0.2 mL) was then added andthe reaction mixture was maintained at 90° C. for an additional 12hours. Upon cooling to room temperature, a solution of potassiumfluoride (1 g) in water (2 mL) was added. This mixture was stirred atroom temperature for 2 hours before it was diluted with chloroform (150mL). The resulting mixture was washed with water (100 mL×3), dried overanhydrous sodium sulfate, and concentrated on a rotary evaporator. Theresidue was taken with chloroform (25 mL) and precipitated in methanol(50 mL) and acetone (50 mL) in sequence. The isolated dark solid wasdissolved in chloroform (25 mL) and heated to boil. Upon cooling to roomtemperature, the chloroform solution was filtered through a 5 μm filter,and the filtrate was added slowly to methanol (50 mL). The precipitateswere collected by filtration, washed with methanol, and dried in vacuum,leading to a deep blue solid as the product (105.0 mg, yield 91.5%). ¹HNMR (CDCl₂CDCl₂ 500 MHz): δ: 8.72 (m, br, 2H), 8.40 (s, br, 4H),7.12-7.45 (m, br, 4H), 4.11 (s, br, 4H), 2.01 (s, br, 2H), 1.15-1.50 (m,br, 64H), 0.84 (s, br, 12H). GPC: M_(n)=11.0K Da, M_(w)=32.1K Da,PDI=2.9. Elemental Analysis (calc. C, 77.65; H, 8.33; N, 2.52): fond C,76.60; H, 7.94; N, 2.47.

Example 10 Preparation of dithienocoronene diimide-based copolymer[P(DTC2OD-T2)]

Preparation of PDI2OD-T2Br2: A mixture of PDI2OD-T2 (1.95 g, 1.75 mmol)and NBS (1.12 g, 6.29 mmol) in dry DMF (100 mL) was heated at 110° C.for 17 hours under nitrogen. After cooling to room temperature, thereaction mixture was evaporated to dryness to give a semi-solid crudeproduct. The crude product was initially purified by columnchromatography (silica gel, dichloromethane:hexanes (2:1, v/v)) to givea mixture of 1,6 and 1,7 isomers which were separated after a secondcolumn chromatography (silica gel, dichloromethane:hexanes (1:1), v/v))to yield pure 1,7 isomer as a deep purple solid (1.0 g, 45% yield).

Preparation of DTC2OD-Br₂: A mixture of PDI2OD-T2Br₂ (347 mg, 0.272mmol) and iodine (147 mg, 0.552 mmol) was dissolved in benzene (200 mL),and exposed to the UV-light for 15 hours in a Rayonet RPR-100photochemical reactor equipped with sixteen RPR 3000 Å lamps. After thephotochemical reaction was done, the precipitate was filtered and washedsuccessively with methanol, acetone and hexane, and dried in a vacuumoven (60° C., overnight) to afford the pure compound as an orange solid(326 mg, 94% yield).

Preparation of P(DTC2OD-T2): The reagents5,5′-bis(trimethylstannyl)-2,2′-bithiophene (11.6 mg, 0.024 mmol),DTC2OD-Br₂ (30 mg, 0.024 mmol), and Pd(PPh₃)₂Cl₂ (0.8 mg, 0.0012 mmol)in anhydrous toluene (4 mL) were heated at 90° C. for 19 h undernitrogen in a sealed flask. After cooling to room temperature, the darkgreen viscous reaction mixture was poured into methanol (20 mL). Afterstirring for 2 hours, the precipitated dark solid was collected bygravity filtration.

Preparation of Electron-Donor Polymers Example 11

Preparation ofpoly[{4,8-bis[(2-hexyldecyl)oxy]benzo[1,2-b:4,5-b′]dithiophene)-2,6-diyl-(3-dodecyl-2,5-thiophenediyl)-2,1,3-benzothiadiazole-4,7-diyl-(4-dodecyl-2,5-thiophenediyl)}-co-[{4,8-bis[(2-hexyldecyl)oxy]benzo[1,2-b:4,5-b′]-dithiophene)-2,6-diyl-(2,5-thiophenediyl)-2,1,3-benzothiadiazole-4,7-diyl-(2,5-thiophenediyl)}](x=0.23; y=0.77

To a Schlenk flask were added4,7-bis(5-bromo-2-thienyl)-2,1,3-benzothiadiazole (46.23 mg, 0.101mmol),4,8-bis[(2-hexyldecyl)oxy]-2,6-bis(1,1,1-trimethyl-stannanyl)benzo[1,2-b:4,5-b′]dithiophene(141.65 mg, 0.135 mmol),4,7-bis(5-bromo-4-dodecyl-2-thienyl)-2,1,3-benzothiadiazole (24.6 mg,0.0309 mmol), Pa₂ dba₃ (4.93 mg, 0.00538 mmol), and P(o-tol)₃ (13.10 mg,0.431 mmol). The flask was degassed and backfilled with nitrogen threetimes. Dry chlorobenzene (20 mL) was injected and the reaction washeated to 130° C. for 18 hours. The reaction was cooled to roomtemperature and the content of the flask was poured into methanol (100mL). The precipitates were collected by filtration and the solids wereextracted with acetone for 1 hour, dichloromethane for 3 hours andchloroform for three hours. Finally, the polymer was extracted withchlorobenzene. The chloroform solution was poured into methanol, and theprecipitates were again collected by filtration, dried under vacuum toafford the title polymer (40 mg).

Example 12 Preparation ofpoly[{4,8-bis[(2-hexyldecyl)oxy]benzo[1,2-b:4,5-b′]dithiophene)2,6-diyl-(3-dodecyl-2,5-thiophenediyl)-2,1,3-benzothiadiazole-4,7-diyl-(4-dodecyl-2,5-thiphenediyl)}-co[{4,8-bis[(2-hexyldecyl)oxy]benzo[1,2-b:4,5-b′]dithiophene)-2,6-diyl-(2,5-thiophenediyl)-2,1,3-benzothiadiazole-4,7-diyl(2,5-thiophenediyl)}](x=0.29; y=0.71)

To a Schlenk flask were added4,8-bis[(2-hexyldecyl)oxy]-2,6-bis(1,1,1-trimethyl-stannanyl)benzo[1,2-b:4,5-b′]dithiophene(129.74 mg, 0.123 mmol),4,7-bis(5-bromo-2-thienyl)-2,1,3-benzothiadiazole (39.53 mg, 0.0863mmol), 4,7-bis(5-bromo-4-dodecyl-2-thienyl)-2,1,3-benzothiadiazole(27.43 mg, 0.345 mmol), Pa₂ dba₃ (4.513 mg, 0.000493 mmol), andP(o-tol)₃ (12.00 mg, 0.394 mmol). The flask was degassed and backfilledwith nitrogen three times. Dry chlorobenzene (20 mL) was injected andthe reaction was heated to 130° C. for 18 hours. The reaction was cooledto room temperature and the content of the flask was poured intomethanol (200 mL). The precipitates were collected by filtration and thesolids were extracted with ethyl acetate for 5 hours, and THF for 5hours. Finally the polymer was extracted with chlorobenzene. Thechloroform solution was poured into methanol, and the precipitates wereagain collected by filtration, dried under vacuum to afford the titlepolymer (64 mg, 49% yield).

Example 13 Preparation ofpoly[{4,8-bis[(2-hexyldecyl)oxy]benzo[1,2-b:4,5-b′]dithiophene)-2,6-diyl-(3-dodecyl-2,5-thiophenediyl)-2,1,3-benzothiadiazole-4,7-diyl-(4-dodecyl-2,5-thiophenediyl)}-co-[{4,8-bis[(2-hexyldecyl)oxy]benzo[1,2-b:4,5-b′]dithiophene)-2,6-diyl-(2,5-thiophenediyl)-2,1,3-benzothiadiazole-4,7-diyl(2,5-thiophenediyl)}](x=0.38; y=0.62)

To a Schlenk flask were added4,8-bis[(2-hexyldecyl)oxy]-2,6-bis(1,1,1-trimethyl-stannanyl)benzo[1,2-b:4,5-b′]dithiophene(117.27 mg, 0.111 mmol),4,7-bis(5-bromo-2-thienyl)-2,1,3-benzothiadiazole (30.62 mg, 0.0668mmol), 4,7-bis(5-bromo-4-dodecyl-2-thienyl)-2,1,3-benzothiadiazole(33.64 mg, 0.0423 mmol), Pa₂ dba₃ (4.08 mg, 0.0045 mmol), and P(o-tol)₃(10.85 mg, 0.0356 mmol). The flask was degassed and backfilled withnitrogen three times. Dry chlorobenzene (20 mL) was injected and thereaction was heated to 130° C. for 18 hours. The reaction was cooled toroom temperature and the content of the flask was poured into methanol(100 mL). The precipitates were collected by filtration and the solidswere extracted with methanol for 8 hours, ethyl acetate for 5 hours, andthen dichloromethane for 15 hours. Finally the polymer was extractedinto chloroform. The chloroform solution was poured into methanol, andthe precipitates were again collected by filtration, dried under vacuumto afford the title polymer 88 mg (72% yield).

Example 14 Preparation ofpoly[{4,8-bis[(2-hexyldecyl)oxy]benzo[1,2-b:4,5-b′]dithiophene)-2,6-diyl-(3-dodecyl-2,5-thiophenediyl)-2,1,3-benzothiadiazole-4,7-diyl-(4-dodecyl-2,5-thiophenediyl)}-co-[{4,8-bis[(2-hexyldecyl)oxy]benzo[1,2-b:4,5-b′]dithiophene)-2,6-diyl-(2,5-thiophenediyl)-2,1,3-benzothiadiazole-4,7-diyl(2,5-thiophenediyl)}](x=0.5; y=0.5)

To a Schlenk flask were added4,8-bis[(2-hexyldecyl)oxy]-2,6-bis(1,1,1-trimethyl-stannanyl)benzo[1,2-b:4,5-b′]dithiophene(600 mg, 0.60 mmol), 4,7-bis(5-bromo-2-thienyl)-2,1,3-benzothiadiazole(137.9 mg, 0.301 mmol),4,7-bis(5-bromo-4-dodecyl-2-thienyl)-2,1,3-benzothiadiazole (229.60 mg,0.289 mmol), Pa₂ dba₃ (22.05 mg, 0.024 mmol), and P(o-tol)₃ (58.63 mg,0.193 mmol). The flask was degassed and backfilled with argon threetimes. Dry chlorobenzene (90 mL) was injected and the reaction washeated to 130° C. for 18 hours. The reaction was cooled to roomtemperature and the content of the flask was poured into methanol (200mL). The precipitates were collected by filtration and the solids wereextracted with methanol for 5 hours, ethyl acetate for 5 hours, hexanesfor 15 hours, and then dichloromethane for 5 hours. Finally the polymerwas extracted into chloroform. The chloroform solution was poured intomethanol, and the precipitates were again collected by filtration, driedunder vacuum to afford the title polymer 511 mg (75% yield).

Example 15 Preparation ofpoly[{4,8-bis[(2-hexyldecyl)oxy]benzo[1,2-b:4,5-b′]dithiophene)-2,6-diyl-(3-dodecyl-2,5-thiophenediyl)-5,6-difluoro-benzo[1,2,5]thiadiazole-4,7-diyl-(4-dodecyl-2,5-thiophenediyl)}-co-[{4,8-bis[(2-hexyldecyl)oxy]benzo[1,2-b:4,5-b′]dithiophene)-2,6-diyl-(2,5-thiophenediyl)-5,6-difluoro-benzo[1,2,5]thiadiazole-4,7-diyl(2,5-thiophenediyl)}](x=0.5; y=0.5)

4,7-Bis-(5-bromo-4-dodecyl-thiophen-2-yl)-5,6-difluoro-benzo[1,2,5]thiadiazole(20.77 mg, 0.025 mmol),4,7-bis-(5-bromo-thiophen-2-yl)-5,6-difluoro-benzo[1,2,5]thiadiazole(12.35 mg, 0.025 mmol),4,8-bis-(2-hexyl-decyloxy)-2,6-bis-trimethylstannanyl-benzo[1,2-b:4,5-b′]dithiophene(52.3 mg, 0.055 mmol), Pd₂(dba)₃ (1.83 mg, 2.0 μmmol), and P(o-Tol)₃(2.43 mg, 8.0 μmol) were combined in a 50-mL flask. The system waspurged with argon before 10 mL of anhydrous chlorobenzene was added. Thereaction mixture was heated at 130° C. for 18 hours. After cooling downto room temperature, the polymer was precipitated out from methanol andfurther purified using Soxhlet extraction with methanol, ethyl acetate,and dichloromethane. The product was extracted with chloroform andweighed 16.0 mg (27.5% yield) after removal of the solvent and beingdried in vacuo.

Example 16 Preparation ofpoly[{4,8-bis[(2-hexyldecyl)oxy]benzo[1,2-b:4,5-b′]dithiophene)-2,6-diyl-(3-dodecyl-2,5-thiophenediyl)-5,6-difluoro-benzo[1,2,5]thiadiazole-4,7-diyl-(4-dodecyl-2,5-thiophenediyl)}-co-[{4,8-bis[(2-hexyldecyl)oxy]benzo[1,2-b:4,5-b′]dithiophene)-2,6-diyl-(2,5-thiophenediyl)-5,6-difluoro-benzo[1,2,5]thiadiazole-4,7-diyl(2,5-thiophenediyl)}](x=0.6; y=0.4)

4,7-Bis-(5-bromo-4-dodecyl-thiophen-2-yl)-5,6-difluoro-benzo[1,2,5]thiadiazole(24.92 mg, 0.03 mmol),4,7-bis-(5-bromo-thiophen-2-yl)-5,6-difluoro-benzo[1,2,5]thiadiazole(9.88 mg, 0.02 mmol),4,8-bis-(2-hexyl-decyl)-2,6-bis-trimethylstannanyl-benzo[1,2-b:4,5-b′]dithiophene(52.3 mg, 0.055 mmol), Pd₂(dba)₃ (1.83 mg, 2.0 μmol), and P(o-Tol)₃(2.43 mg, 8.0 μmol) were combined in a 50-mL flask. The system waspurged with argon before 10 mL of anhydrous chlorobenzene was added. Thereaction mixture was heated at 131° C. for 18 hours. After cooling downto room temperature, the polymer was precipitated out from 150 ml ofmethanol and further purified by Soxhlet extraction with methanol,acetone, hexane, ethyl acetate, and dichloromethane. The product wasextracted with chloroform and weighed 38.0 mg (64.0% yield) afterremoval of the solvent and being dried in vacuo.

Example 17 Preparation ofpoly[{4,8-bis[(2-hexyldecyl)oxy]benzo[1,2-b:4,5-b′]dithiophene)-2,6-diyl-(3-dodecyl-2,5-thiophenediyl)-5,6-difluoro-benzo[1,2,5]thiadiazole-4,7-diyl-(4-dodecyl-2,5-thiophenediyl)}-co-[{4,8-bis[(2-hexyldecyl)oxy]benzo[1,2-b:4,5-b′]dithiophene)-2,6-diyl-(2,5-thiophenediyl)-5,6-difluoro-benzo[1,2,5]thiadiazole-4,7-diyl-(2,5-thiophenediyl)}](x=0.7; y=0.3)

4,7-Bis-(5-bromo-4-dodecyl-thiophen-2-yl)-5,6-difluoro-benzo[1,2,5]thiadiazole(29.08 mg, 0.035 mmol),4,7-bis-(5-bromo-thiophen-2-yl)-5,6-difluoro-benzo[1,2,5]thiadiazole(7.413 mg, 0.015 mmol),4,8-bis-(2-hexyl-decyloxy)-2,6-bis-trimethylstannanyl-benzo[1,2-b:4,5-b′]dithiophene(52.3 mg, 0.055 mmol), Pd₂(dba)₃ (1.83 mg, 2.0 μmol), and P(o-Tol)₃(2.43 mg, 8.0 μmol) were combined in a 50-mL flask. The system waspurged with argon before 10 mL of anhydrous chlorobenzene was added. Thereaction mixture was heated at 135° C. for 18 hours. After cooling downto room temperature, the polymer was precipitated out from methanol andfurther purified using Soxhlet extraction with methanol, ethyl acetate,dichloromethane. The product was extracted with chloroform and weighed48.0 mg (77.5% yield) after removal of the solvent and being dried invacuo.

Example 18 Preparation ofpoly[{4,8-bis[(2-hexyldecyl)oxy]benzo[1,2-b:4,5-b′]dithiophene)-2,6-diyl-(3-dodecyl-2,5-thiophenediyl)-5,6-difluro-benzo[1,2,5]thiadiazole-4,7-diyl-(4-dodecyl-2,5-thiophenediyl)}-co-[{4,8-bis[(2-hexyldecyl)oxy]benzo[1,2-b:4,5-b′]dithiophene)-2,6-diyl-(2,5-thiophenediyl)-5,6-difluoro-benzo[1,2,5]thiadiazole-4,7-diyl-(2,5-thiophenediyl)}](x=0.8; y=0.2)

4,7-Bis-(5-bromo-4-dodecyl-thiophen-2-yl)-5,6-difluoro-benzo[1,2,5]thiadiazole(33.23 mg, 0.04 mmol),4,7-bis-(5-bromo-thiophen-2-yl)-5,6-difluoro-benzo[1,2,5]thiadiazole(4.94 mg, 0.01 mmol),4,8-bis-(2-hexyl-decyloxy)-2,6-bis-trimethylstannanyl-benzo[1,2-b:4,5-b′]dithiophene(52.3 mg, 0.055 mmol), Pd₂(dba)₃ (1.83 mg, 2.0 μmol), and P(o-Tol)₃(2.43 mg, 8.0 μmol) were combined in a 50-mL flask. The system waspurged with argon before 10 mL of anhydrous chlorobenzene was added. Thereaction mixture was heated at 135° C. for 18 hours. After cooling downto room temperature, the polymer was precipitated out from methanol andfurther purified using Soxhlet extraction with methanol, acetone,hexane, ethyl acetate, and dichloromethane. The product was extractedwith chloroform and weighed 36.0 mg (60% yield) after removal of thesolvent and being dried in vacuo.

Example 19 Preparation ofpoly[{4,8-bis[(2-hexyldecyl)oxy]benzo[1,2-b:4,5-b′]dithiophene)-2,6-diyl-(3-dodecyl-2,5-thiophenediyl)-5,6-difluro-benzo[1,2,5]thiadiazole-4,7-diyl-(4-dodecyl-2,5-thiophenediyl)}-co-[{4,8-bis[(2-butyloctyl)oxy]benzo[1,2-b:4,5-b′]dithiophene)-2,6-diyl-(3-dodecyl-2,5-thiophenediyl)-benzo[1,2,5]thiadiazole-4,7-diyl-(4-dodecyl-2,5-thiophenediyl)}](x=0.5; y=0.5)

The reagents4,8-bis-(2-butyloctyloxy)-2,6-bis-trimethylstannanyl-benzo[1,2-b:4,5-b′]dithiophene(70 mg, 0.08 mmol),4,7-bis-(5-bromo-4-dodecyl-thiophen-2-yl)-5,6-difluoro-benzo[1,2,5]thiadiazole(33.87 mg, 0.04 mmol),4,7-bis-(5-bromo-4-dodecyl-thiophen-2-yl)-benzo[1,2,5]thiadiazole (31.45mg, 0.04 mmol), Pd₂(dba)₃ (2.9 mg, 0.0032 mmol), and P(o-tolyl)₃ (3.85mg, 0.0127 mmol) in anhydrous chlorobenzene (10 mL) were heated at 135°C. for 16 h under nitrogen in a sealed flask. After cooling to roomtemperature, the dark purple viscous reaction mixture was poured intomethanol (100 mL). The final precipitated polymer was collected byvacuum filtration and dried in a vacuum oven to afford the polymer as ablack solid (83.3 mg, 87% yield).

Example 20 Preparation ofpoly[{4,8-bis[(2-hexyldecyl)oxy]benzo[1,2-b:4,5-b′]dithiophene)-2,6-diyl-(3-dodecyl-2,5-thiophenediyl)-5-chloro-2,1,3-benzothiadiazole-4,7-diyl-(4-dodecyl-2,5-thiophenediyl)}-co-[{4,8-bis[(2-hexyldecyl)oxy]benzo[1,2-b:4,5-b′]dithiophene)-2,6-diyl-(2,5-thiophenediyl)-5-chloro-2,1,3-benzothiadiazole-4,7-diyl-(2,5-thiophenediyl)}](x=0.5; y=0.5)

4,8-Bis[(2-hexyldecyl)oxy]-2,6-bis(1,1,1-trimethyl-stannanyl)benzo[1,2-b:4,5-b′]dithiophene(110 mg, 0.110 mmol),4,7-bis(5-bromo-2-thienyl)-5-chloro-2,1,3-benzothiadiazole (27.18 mg,0.0552 mmol),4,7-bis(5-bromo-4-dodecyl-2-thienyl)-5-chloro-2,1,3-benzothiadiazole(43.93 mg, 0.053 mmol), Pd₂ dba₃ (4.04 mg, 0.00441 mmol), and P(o-tol)₃(10.75 mg, 0.0353 mmol) were placed in a Schlenk flask. The flask wasdegassed and backfilled with argon three times. Dry chlorobenzene (10mL) was injected and the reaction was heated to 130° C. for 18 hr. Thereaction was cooled to room temperature and the contents of the flaskwas poured into methanol (100 mL). The precipitates were collected byfiltration and the solids were extracted with methanol for 3 hours,ethyl acetate for 3 hours, then dichloromethane for 18 hours. Finallythe polymer was extracted into chloroform. The chloroform solution waspoured into methanol, and the precipitates were again collected byfiltration, dried under vacuum to afford the polymer (94 mg, 72% yield).

Example 21 Preparation ofpoly[{4,8-bis[(2-hexyldecyl)oxy]benzo[1,2-b:4,5-b′]dithiophene)-2,6-diyl-(3-dodecyl-2,5-thiophenediyl)-5-chloro-2,1,3-benzothiadiazole-4,7-diyl-(4-dodecyl-2,5-thiophenediyl)}-co-[{4,8-bis[(2-hexyldecyl)oxy]benzo[1,2-b:4,5-b′]dithiophene)-2,6-diyl-(2,5-thiophenediyl)-5-chloro-2,1,3-benzothiadiazole-4,7-diyl-(2,5-thiophenediyl)}](x=0.45; y=0.55)

4,8-Bis[(2-hexyldecyl)oxy]-2,6-bis(1,1,1-trimethyl-stannanyl)benzo[1,2-b:4,5-b′]dithiophene(104.66 mg, 0.105 mmol),4,7-bis(5-bromo-2-thienyl)-5-chloro-2,1,3-benzothiadiazole (27.10 mg,0.055 mmol),4,7-bis(5-bromo-4-dodecyl-2-thienyl)-5-chloro-2,1,3-benzothiadiazole(37.32 mg, 0.045 mmol), Pd₂ dba₃ (3.66 mg, 0.0042 mmol), and P(o-tol)₃(9.76 mg, 0.0336 mmol) were placed in a Schlenk flask. The flask wasdegassed and backfilled with argon three times. Dry chlorobenzene (20mL) was injected and the reaction was heated to 130° C. for 18 hr. Thereaction was cooled to room temperature and the contents of the flaskwas poured into methanol (100 mL). The precipitates were collected byfiltration and the solids were extracted with methanol for 3 hours,ethyl acetate for 3 hours, then dichloromethane for 18 hours. Finallythe polymer was extracted into chloroform. The chloroform solution waspoured into methanol, and the precipitates again were collected byfiltration, then dried under vacuum to afford the polymer (102 mg, 86.4%yield).

Example 22 Preparation ofpoly[{4,8-bis[(2-hexyldecyl)oxy]benzo[1,2-b:4,5-b′]dithiophene)-2,6-diyl-(3-dodecyl-2,5-thiophenediyl)-5-chloro-2,1,3-benzothiadiazole-4,7-diyl-(4-dodecyl-2,5-thiophenediyl)}-co-[{4,8-bis[(2-hexyldecyl)oxy]benzo[1,2-b:4,5-b′]dithiophene)-2,6-diyl-(2,5-thiophenediyl)-5-chloro-2,1,3-benzothiadiazole-4,7-diyl-(2,5-thiophenediyl)}](x=0.4; y=0.6)

4,8-Bis[(2-hexyldecyl)oxy]-2,6-bis(1,1,1-trimethyl-stannanyl)benzo[1,2-b:4,5-b′]dithiophene(104.66 mg, 0.105 mmol),4,7-bis(5-bromo-2-thienyl)-5-chloro-2,1,3-benzothiadiazole (29.56 mg,0.06 mmol),4,7-bis(5-bromo-4-dodecyl-2-thienyl)-5-chloro-2,1,3-benzothiadiazole(33.17 mg, 0.04 mmol), Pd₂ dba₃ (3.66 mg, 0.0042 mmol), and P(o-tol)₃(9.76 mg, 0.0336 mmol) were placed in a Schlenk flask. The flask wasdegassed and backfilled with argon three times. Dry chlorobenzene (20mL) was injected and the reaction was heated to 130° C. for 18 hr. Thereaction was cooled to room temperature and the content of the flask waspoured into methanol (100 mL). The precipitates were collected byfiltration and the solids were extracted with methanol for 3 hours,ethyl acetate for 3 hours, then dichloromethane for 18 hours. Finallythe polymer was extracted into chlorobenzene. The chlorobenzene solutionwas poured into methanol, and the precipitates again were collected byfiltration, then dried under vacuum to afford the polymer (81.7 mg,76.3% yield).

Example 23 Preparation ofpoly[{4,8-bis[(2-butyloctyl)oxy]benzo[1,2-b:4,5-b′]dithiophene)-2,6-diyl-(3-dodecyl-2,5-thiophenediyl)-5,6-dichloro-benzo[1,2,5]thiadiazole-4,7-diyl-(4-dodecyl-2,5-thiophenediyl)}-co-[{4,8-bis[(2-butyloctyl)oxy]benzo[1,2-b:4,5-b′]dithiophene)-2,6-diyl-(3-dodecyl-2,5-thiophenediyl)-benzo[1,2,5]thiadiazole-4,7-diyl-(4-dodecyl-2,5-thiophenediyl)}](x=0.5; y=0.5)

The reagents4,8-bis-(2-butyloctyloxy)-2,6-bis-trimethylstannanyl-benzo[1,2-b:4,5-b′]dithiophene(60.0 mg, 0.068 mmol),4,7-bis-(5-bromo-4-dodecyl-thiophen-2-yl)-5,6-dichloro-benzo[1,2,5]thiadiazole(29.3 mg, 0.034 mmol),4,7-bis-(5-bromo-4-dodecyl-thiophen-2-yl)-benzo[1,2,5]thiadiazole (26.9mg, 0.034 mmol), Pd₂(dba)₃ (2.5 mg, 0.0027 mmol), and P(o-tolyl)₃ (3.3mg, 0.011 mmol) in anhydrous chlorobenzene (10 mL) were heated at 135°C. for 16 hr under nitrogen in a sealed flask. After cooling to roomtemperature, the dark purple viscous reaction mixture was poured intomethanol (100 mL). The final precipitated polymer was collected byvacuum filtration and dried in a vacuum oven to afford the polymer as ablack solid (78 mg, 93.8% yield).

Example 24 Preparation ofpoly[{4,8-bis[(2-butyloctyl)oxy]benzo[1,2-b:4,5-b′]dithiophene)-2,6-diyl-(3-dodecyl-2,5-thiophenediyl)-5-fluoro-benzo[1,2,5]thiadiazole-4,7-diyl-(4-dodecyl-2,5-thiophenediyl)}-co-[{4,8-bis[(2-butyloctyl)oxy]benzo[1,2-b:4,5-b′]dithiophene)-2,6-diyl-(3-dodecyl-2,5-thiophenediyl)-benzo[1,2,5]thiadiazole-4,7-diyl-(4-dodecyl-2,5-thiophenediyl)}](x=0.5; y=0.5)

4,7-Bis-(5-bromo-4-dodecyl-thiophen-2-yl)-5-fluoro-benzo[1,2,5]thiadiazole(20.32 mg, 0.025 mmol),4,7-bis-(5-bromo-4-dodecyl-thiophen-2-yl)-benzo[1,2,5]thiadiazole (19.87mg, 0.025 mmol),4,8-bis-(2-butyl-octyl)-2,6-bis-trimethylstannanyl-benzo[1,2-b:4,5-b′]dithiophene(44.23 mg, 0.050 mmol), Pd₂(dba)₃ (1.83 mg, 2.0 μmol), and P(o-Tol)₃(2.43 mg, 8.0 μmol) were combined in a 50-mL flask. The system waspurged with argon before 10 mL of anhydrous chlorobenzene was added. Thereaction mixture was heated at 132° C. for 22 hours. After cooling downto room temperature, the polymer was precipitated out from methanol andfurther purified by Soxhlet extraction with methanol, ethyl acetate,hexane, and dichloromethane. The product was extracted withdichloromethane and weighed 43 mg (71.6% yield) after removal of thesolvent and drying in vacuo.

Example 25 Preparation ofpoly[{4,8-bis[(5-(2-hexyldecyl)thiophen-2-yl]benzo[1,2-b:4,5-b′]dithiophene)-2,6-diyl-(3-dodecyl-2,5-thiophenediyl)-5-chloro-2,1,3-benzothiadiazole-4,7-diyl-(4-dodecyl-2,5-thiophenediyl)}-co-[{4,8-bis[(5-(2-hexyldecyl)thiophen-2-yl]benzo[1,2-b:4,5-b′]dithiophene)-2,6-diyl-(2,5-thiophenediyl)-5-chloro-2,1,3-benzothiadiazole-4,7-diyl-(2,5-thiophenediyl)}](x=0.45; y=0.55)

Preparation of4,8-bis-[5-(2-hexyldecyl)-thiophen-2-yl]-1,5-dithia-s-indacene:2-(2-Hexyldecyl)thiophene (7.12 g, 0.013 mol) was added into 500 mLflask. The system was vacuumed and backfilled with argon three timesbefore 250 mL of anhydrous THF was added. Butyl lithium (2.5 M inhexane, 8.8 mL, 0.022 mol) was added dropwise after the system wascooled to 0° C. for 30 minutes. The resulting mixture was stirred atroom temperature for 1.5 hours before 2.2 g of1,5-dithia-s-indacene-4,8-dione (0.01 mol) was added in the flow ofargon. The mixture was heated at 60° C. for 2 hours before being cooledto room temperature. The solution of 9.5 g of SnCl₂ in 150 mL of 30% HClwas added slowly into the reaction system. The mixture was heated at 60°C. for another 3 hours before being cooled to room temperature. Hexane(500 mL) was added and the mixture was washed with saturated Na₂CO₃solution until no white solid was observed and then dried with MgSO₄.After the removal of solvent,4,8-bis-[5-(2-hexyldecyl)-thiophen-2-yl]-1,5-dithia-s-indacene (5.0 g,yield 62.2%) was obtained by purification with chromatography withhexane as eluent. ¹H NMR (CDCl₃, 500 MHz): δ 7.67 (d, 2H, J=5.5 Hz), δ7.48 (d, 2H, J=5.5 Hz), δ 7.32 (d, 2H, J=3.5 Hz), δ 6.91 (d, 2H, J=3.5Hz), δ 2.88 (d, 4H, J=6.5 Hz), δ 1.76 (s, 2H), δ 1.38˜1.32 (m, 48H), δ0.91 (m, 12H).

Preparation of4,8-bis-[5-(2-hexyldecyl)-thiophen-2-yl]-2,6-bis-trimethylstannanyl-1,5-dithia-s-indacene:4,8-Bis-[5-(2-hexyldecyl)-thiophen-2-yl]-1,5-dithia-s-indacene (2.06 g,2.56 mmol) was added into 200 mL flask. The system was vacuumed andbackfilled with argon 3 times before 80 mL of anhydrous THF wasinjected. n-Butyl lithium (2.5 M in hexane, 2.3 mL, 5.6 mmol) was addedafter the mixture was cooled to −78° C. The mixture was stirred at −78°C. for 30 minutes and then at room temperature for one more hour. Thesystem was cooled down to −78° C. again before trimethyltin chloride(0.5 g, 2.5 mmol) was added in portions. Stirring was continuedovernight at room temperature. Hexane (200 mL) was added and the organiclayer was washed with 150 mL of water. The aqueous layer was extractedwith 100 mL of hexane twice. The combined organic layer was dried overanhydrous Na₂SO₄. Removal of the solvent under vacuum yielded a yellowliquid (2.2 g, 76.0% yield) as the final product after drying in vacuoovernight. ¹H NMR (CDCl₃, 500 MHz): δ 7.57 (s, 2H), δ 7.21 (d, 2H, J=3.0Hz), δ 6.78 (d, 2H, J=3.5 Hz), δ 2.76 (d, 4H, J=6.5 Hz), δ 1.62 (s, 2H),δ 1.26˜1.19 (m, 48H), δ 0.76 (m, 12H), δ 0.29 (m, 18H).

4,8-Bis-[5-(2-hexyldecyl)-thiophen-2-yl]-2,6-bis-trimethylstannanyl-1,5-dithia-s-indacene(118.5 mg, 0.105 mmol),4,7-bis(5-bromo-2-thienyl)-5-chloro-2,1,3-benzothiadiazole (27.10 mg,0.055 mmol),4,7-bis(5-bromo-4-dodecyl-2-thienyl)-5-chloro-2,1,3-benzothiadiazole(37.32 mg, 0.045 mmol), Pd₂ dba₃ (3.66 mg, 0.0042 mmol), and P(o-tol)₃(9.76 mg, 0.0336 mmol) were placed in a Schlenk flask. The flask wasdegassed and backfilled with argon three times. Dry chlorobenzene (20mL) was injected and the reaction was heated to 130° C. for 18 hr. Thereaction was cooled to room temperature and the content of the flask waspoured into methanol (100 mL). The precipitates were collected byfiltration and the solids were extracted with methanol for 3 hours,ethyl acetate for 3 hours, then dichloromethane for 18 hours. Finally,the polymer was extracted into chloroform. The chloroform solution waspoured into methanol, and the precipitates again were collected byfiltration, then dried under vacuum to afford the polymer (59 mg, 43.3%yield).

Example 26 Preparation ofpoly[{4,8-bis[5-(2-hexyldecyl)thiophen-2-yl]benzo[1,2-b:4,5-b′]dithiophene)-2,6-diyl-(3-dodecyl-2,5-thiophenediyl)-5-chloro-2,1,3-benzothiadiazole-4,7-diyl-(4-dodecyl-2,5-thiophenediyl)}-co-[{4,8-bis[5-(2-hexyldecyl)thiophen-2-yl]benzo[1,2-b:4,5-b′]dithiophene)-2,6-diyl-(2,5-thiophenediyl)-5-chloro-2,1,3-benzothiadiazole-4,7-diyl-(2,5-thiophenediyl)}](x=0.35; y=0.65)

4,8-Bis-[5-(2-hexyldecyl)-thiophen-2-yl]-2,6-bis-trimethylstannanyl-1,5-dithia-s-indacene(118.5 mg, 0.105 mmol),4,7-bis(5-bromo-2-thienyl)-5-chloro-2,1,3-benzothiadiazole (32.02 mg,0.065 mmol),4,7-bis(5-bromo-4-dodecyl-2-thienyl)-5-chloro-2,1,3-benzothiadiazole(29.03 mg, 0.035 mmol), Pd₂ dba₃ (3.66 mg, 0.0042 mmol), and P(o-tol)₃(9.76 mg, 0.0336 mmol) were placed in a Schlenk flask. The flask wasdegassed and backfilled with argon three times. Dry chlorobenzene (20mL) was injected and the reaction was heated to 130° C. for 18 hr. Thereaction was cooled to room temperature and the contents of the flaskwas poured into methanol (100 mL). The precipitates were collected byfiltration and the solids were extracted with methanol for 3 hours,ethyl acetate for 3 hours, then dichloromethane for 18 hours. Finally,the polymer was extracted into chloroform. The chloroform solution waspoured into methanol, and the precipitates again were collected byfiltration, then dried under vacuum to afford the polymer (110 mg, 84.9%yield).

Example 27 Preparation ofpoly[{4,8-bis[5-(2-hexyldecyl)thiophen-2-yl]benzo[1,2-b:4,5-b′]dithiophene)-2,6-diyl-(3-dodecyl-2,5-thiophenediyl)-5-chloro-2,1,3-benzothiadiazole-4,7-diyl-(4-dodecyl-2,5-thiophenediyl)}-co-[{4,8-bis[5-(2-hexyldecyl)thiophen-2-yl]benzo[1,2-b:4,5-b′]dithiophene)-2,6-diyl-(2,5-thiophenediyl)-5-chloro-2,1,3-benzothiadiazole-4,7-diyl-(2,5-thiophenediyl)}](x=0.3; y=0.7)

4,8-Bis-[5-(2-hexyldecyl)-thiophen-2-yl]-2,6-bis-trimethylstannanyl-1,5-dithia-s-indacene(118.5 mg, 0.105 mmol),4,7-bis(5-bromo-2-thienyl)-5-chloro-2,1,3-benzothiadiazole (34.49 mg,0.07 mmol),4,7-bis(5-bromo-4-dodecyl-2-thienyl)-5-chloro-2,1,3-benzothiadiazole(24.88 mg, 0.03 mmol), Pa₂ dba₃ (3.66 mg, 0.0042 mmol), P(o-tol)₃ (4.86mg, 0.0336 mmol) were placed in a Schlenk flask. The flask was degassedand backfilled with argon three times. Dry chlorobenzene (20 mL) wasinjected and the reaction was heated to 130° C. for 18 hr. The reactionwas cooled to rt and the contents of the flask was poured into methanol(100 mL). The precipitates were collected by filtration and the solidswere extracted with methanol for 3 hr, ethyl acetate for 3 hr,dichloromethane for 18 hr. Finally the polymer was extracted intochloroform. The chloroform solution was poured into methanol, and theprecipitates were again collected by filtration, dried under vacuum toafford the polymer (70.0 mg, 61.3%).

Example 28 Preparation ofpoly[{4,8-bis[5-(2-hexyldecyl)thiophen-2-yl]benzo[1,2-b:4,5-b′]dithiophene)-2,6-diyl-(3-dodecyl-2,5-thiophenediyl)-5,6-difluoro-benzo[1,2,5]thiadiazole-4,7-diyl-(4-dodecyl-2,5-thiophenediyl)}-co-[{4,8-bis[5-(2-hexyldecyl)thiophen-2-yl]benzo[1,2-b:4,5-b′]dithiophene)-2,6-diyl-(2,5-thiophenediyl)-5,6-difluoro-benzo[1,2,5]thiadiazole-4,7-diyl-(2,5-thiophenediyl)}](x=0.5; y=0.5)

4,8-Bis-[5-(2-hexyldecyl)-thiophen-2-yl]-2,6-bis-trimethylstannanyl-1,5-dithia-s-indacene(118.5 mg, 0.105 mmol),4,7-bis-(5-bromo-thiophen-2-yl)-5,6-difluoro-benzo[1,2,5]thiadiazole(24.71 mg, 0.050 mmol),4,7-bis-(5-bromo-4-dodecyl-thiophen-2-yl)-5,6-difluoro-benzo[1,2,5]thiadiazole(41.54 mg, 0.050 mmol), Pa₂ dba₃ (3.66 mg, 0.0042 mmol), P(o-tol)₃ (9.76mg, 0.0336 mmol) were placed in a Schlenk flask. The flask was degassedand backfilled with argon three times. Dry chlorobenzene (20 mL) wasinjected and the reaction was heated to 130° C. for 18 hr. The reactionwas cooled to rt and the contents of the flask was poured into methanol(100 mL). The precipitates were collected by filtration and the solidswere extracted with methanol for 3 hr, ethyl acetate for 3 hr,dichloromethane for 18 hr. Finally the polymer was extracted intochloroform. The chloroform solution was poured into methanol, and theprecipitates were again collected by filtration, dried under vacuum toafford the polymer (52.0 mg, 39.5%).

Example 29 Preparation ofpoly[{2,6-(4,8-didodecylbenzo[1,2-b:4,5-b′]dithiophene)}-alt{5,5-(1,4-bis(2-butyloctyl)-3,6-dithiophen-2-yl-1,4-dihydropyrrolo[3,2-b]pyrrole-2,5-dione)}]

To a 10 mL microwave tube,2,6-bis(trimethylstannyl)-4,8-didodecylbenzo[1,2-b:4,5-b′]dithiophene(51.2 mg, 60 μmol),3,6-bis-(5-bromo-thiophen-2-yl)-1,4-bis-(2-butyloctyl)-1,4-dihydropyrrolo[3,2-b]pyrrole-2,5-dione(47.7 mg, 60 μmol), Pd₂(dba)₃ (2.7 mg, 5 mol %) andtri(o-tolyl)phosphine (3.7 mg, 20 mol %) were mixed in anhydrous toluene(5 mL) under argon. Then the tube was heated to 180° C. in 30 minutesand kept at this temperature for 270 minutes by a CEM Discover Microwavereactor. After cooling, it was poured into MeOH (50 mL), filtered anddried in a vacuum oven to give a dark brown solid (68.4 mg). Using aSoxhlet setup, the crude product was extracted successively, with MeOH,hexane, ethyl acetate, THF and chloroform. The chloroform extract waspoured into MeOH (100 mL) and the solid was collected. Finally, a darkbrown solid (62.1 mg, yield 89%, Mn=792 kDa, d=2.7) was obtained.Elemental Analysis: Calcd. C, 74.56; H, 9.21; N, 2.42. Found: C, 74.42,H, 9.18, N, 2.55.

Example 30 Preparation ofpoly[{2,6-(4,8-bis(2-ethylhexyl)benzo[1,2-b:4,5-b′]dithiophene)}-alt{5,5-(1,4-bis(2-butyloctyl)-3,6-dithiophen-2-yl-1,4-dihydropyrrolo[3,2-b]pyrrole-2,5-dione)}]

To a 10 mL microwave tube,2,6-bis(trimethylstannyl)-4,8-bis(2-ethylhexyl)[1,2-b:4,5-b′]dithiophene(44.4 mg, 60 μmol),3,6-bis-(5-bromo-thiophen-2-yl)-1,4-bis-(2-butyloctyl)-1,4-dihydropyrrolo[3,2-b]pyrrole-2,5-dione(47.7 mg, 60 μmol), Pd₂(dba)₃ (2.7 mg, 5 mol %) andtri(o-tolyl)phosphine (3.7 mg, 20 mol %) were mixed in anhydrous toluene(5 mL) under argon. Then the tube was heated to 180° C. in 30 minutesand kept at this temperature for 270 minutes by a CEM Discover Microwavereactor. After cooling, it was poured into MeOH (50 mL), filtered anddried in a vacuum oven to give a dark brown solid (61.0 mg). Using aSoxhlet setup, the crude product was extracted successively with MeOH,hexane, ethyl acetate, THF and chloroform. The chloroform extract waspoured into MeOH (100 mL) and the solid was collected. Finally, a darkbrown solid (54.0 mg, yield 86%, Mn=26 kDa, d=27) was obtained.Elemental Analysis: Calcd. C, 73.37; H, 8.66; N, 2.67. Found: C, 73.06,H, 8.50, N, 2.80.

Example 31 Preparation ofpoly[{2,6-(4,8-bis(2-ethylhexyl)benzo[1,2-b:4,5-b′]dithiophene)}-alt-{5,5-(1,4-bis(2-butyloctyl)-3,6-dithiophen-2-yl-1,4-dihydropyrrolo[3,2-b]pyrrole-2,5-dione)}]

To a 10 mL microwave tube,2,6-bis(trimethylstannyl)-4,8-didodecyloxybenzo[1,2-b:4,5-b′]dithiophene(53.1 mg, 60 μmol),3,6-bis-(5-bromo-thiophen-2-yl)-1,4-bis-(2-butyloctyl)-1,4-dihydropyrrolo[3,2-b]pyrrole-2,5-dione(47.7 mg, 60 μmol), Pd₂(dba)₃ (2.7 mg, 5 mol %) andtri(o-tolyl)phosphine (3.7 mg, 20 mol %) were mixed in anhydrous toluene(5 mL) under argon. Then the tube was heated to 180° C. in 30 minutesand kept at this temperature for 270 minutes by a CEM Discover Microwavereactor. After cooling, it was poured into MeOH (50 mL), filtered anddried in a vacuum oven to give a dark brown solid. Using a Soxhletsetup, the crude product was extracted successively with MeOH, hexane,ethyl acetate, ether and dichloromethane. The dichloromethane extractwas poured into MeOH (100 mL) and the solid was collected. Finally, adark brown solid (45.0 mg, yield 63%, Mn=49 kDa, d=30) was obtained.Elemental Analysis: Calcd. C, 72.55, H, 8.96, N, 2.35. Found: C, 72.28,H, 8.85, N, 2.48.

Example 32 Preparation ofpoly[{4,8-bis[5-(2-hexyldecyl)thiophen-2-yl]benzo[1,2-b:4,5-b′]dithiophene)-2,6-diyl-(3-dodecyl-2,5-thiophenediyl)-benzo[1,2,5]thiadiazole-4,7-diyl-(4-dodecyl-2,5-thiophenediyl)}-co-[{4,8-bis[5-(2-hexyldecyl)thiophen-2-yl]benzo[1,2-b:4,5-b′]dithiophene)-2,6-diyl-(2,5-thiophenediyl)-benzo[1,2,5]thiadiazole-4,7-diyl-(2,5-thiophenediyl)}](x=0.5; y=0.5)

4,8-Bis-[5-(2-hexyl-decyl)-thiophen-2-yl]-2,6-bis-trimethylstannanyl-1,5-dithia-s-indacene(118.5 mg, 0.105 mmol),4,7-bis(5-bromo-2-thienyl)-2,1,3-benzothiadiazole (22.91 mg, 0.05 mmol),4,7-bis(5-bromo-4-dodecyl-2-thienyl)-2,1,3-benzothiadiazole (39.74 mg,0.05 mmol), Pa₂ dba₃ (3.66 mg, 0.004 mmol), P(o-tol)₃ (4.86 mg, 0.016mmol) were placed in a Schlenk flask. The flask was degassed andbackfilled with argon three times. Dry chlorobenzene (20 mL) wasinjected and the reaction was heated to 130° C. for 18 hours. Thereaction was cooled to room temperature and the contents of the flaskwere poured into methanol (100 mL). The precipitates were collected byfiltration and the solids were extracted with methanol for 6 hours,ethyl acetate for 16 hours, and dichloromethane for 24 hours. Finallythe polymer was extracted into chloroform. The chloroform solution waspoured into methanol, and the precipitates were again collected byfiltration, dried under vacuum to afford the polymer (60.0 mg, 46.8%).Elemental Analysis: Found (%): C, 72.16; H, 8.18; N, 2.27.

Example 33 Preparation ofpoly[{2,6-(4,8-bis[5-(2-hexyldecyl)-2-thienyl]benzo[1,2-b:4,5-b′]dithiophene)}-alt{5,5-(1,4-bisdecyl-3,6-dithiophen-2-yl-1,4-dihydropyrrolo[3,2-b]pyrrole-2,5-dione)}]

To a 100 mL storage vessel,2,6-bis(trimethylstannyl)-4,8-bis[5-(2-hexyldecyl)-2-thienyl]benzo[1,2-b:4,5-b′]dithiophene(105.8 mg, 93.7 μmol),3,6-bis-(5-bromo-thiophen-2-yl)-1,4-bisdecyl-1,4-dihydropyrrolo[3,2-b]pyrrole-2,5-dione(69.2 mg, 93.7 μmol), Pd₂(dba)₃ (4.3 mg, 5 mol %) andtri(o-tolyl)phosphine (5.7 mg, 20 mol %) were mixed in anhydrouschlorobenzene (8 mL) under argon. Then the tube was heated at 135° C.for 16 hours. After cooling, it was poured into MeOH (50 mL), filteredand dried in a vacuum oven. Using a Soxhlet setup, the crude product wasextracted successively with MeOH, ethyl acetate, dichloromethane, andchloroform. The chloroform extract was poured into MeOH (100 mL) and thesolid was collected. Finally, a dark blue solid (76 mg, yield 59%, hightemperature GPC in trichlorobenzene: Mn=21.6 kDa, d=1.97) was obtained.Elemental Analysis:

Calcd. C, 73.10; H, 8.62; N, 2.03. Found: C, 72.83, H, 8.51, N, 2.12.

Example 34 Preparation of naphthodithiophene-based donor polymer

Naphthalene-2,6-diol (16.0 g, 0.1 mol) and NaH (6.0 g, 0.25 mol) wascombined together in a 500 mL flask under argon. The mixture was cooledto −78° C. before the addition of anhydrous DMF (200 mL) by injection.The mixture emitted a significant amount o gas. Stirring was continuedat room temperature for 2 hours. Dimethyl sulfate (31.5 g, 0.25 mol) wasadded dropwise after the mixture was cooled to −78° C. again. Thereaction was continued overnight at room temperature before 200 mL ofanhydrous DMF was added. 2,6-Dimethoxy-naphthalene (16.0 g, ˜85.1%yield) was collected as a white powder by filtration and washed withwater and methanol before drying under vacuum. ¹H NMR (CDCl₃, 500 MHz):δ 7.67 (d, 2H, J=8.5 Hz), δ 7.17 (d×d, 2H, J=8.5 Hz×2.5 Hz), δ 7.13 (d,2H, J=2.5 Hz), δ 7.13 (d, 2H, J=2.5 Hz), δ 3.93 (s, 6H).

To a 200 mL Schlenk flask, 2,6-dimethoxy-naphthalene (3.76 g, 20.0 mmol)was added. The system was vacuumed and backfilled with argon 3 timesbefore 100 mL of anhydrous THF was added. After the mixture was cooledto 0° C. for 30 minutes, n-butyllithium (34 mL, 2.5 M, 85.0 mmol) wasinjected dropwise. The resulting mixture was stirred at room temperaturefor 4 hours before being cooled to −78° C.2-(2,2-Diethoxy-ethyldisulfanyl)-1,1-diethoxyethane (26.6 g, 103 mmol)was injected in one portion. The dry ice bath was removed 5 minuteslater and the mixture was stirred overnight. Water (100 mL) was added toquench the reaction and the mixture was stirred at room temperature for10 minutes. Hexane (150 mL×3) was used to extract the product and thecombined organic layer was dried with anhydrous Na₂SO₄. Methanol (150mL) was added and2,6-bis-(2,2-diethoxy-ethylsulfanyl)-3,7-dimethoxy-naphthalene (5.0 g,˜52.0% yield) as a yellow solid was collected by filtration and washedwith methanol and dried under vacuum. ¹H NMR (CDCl₃, 500 MHz): δ 7.62(s, 2H), δ 7.00 (s, 2H), 6 (t, 2H, J=2.5 Hz), δ 3.99 (s, 6H), δ 3.73 (m,4H), δ 3.60 (m, 4H), δ 3.23 (d, 4H, J=2.5 Hz), δ 1.23 (t, 12H, J=9.0Hz).

2,6-Bis-(2,2-diethoxy-ethylsulfanyl)-3,7-dimethoxy-naphthalene (5.0 g,10.3 mmol) and 6.8 g of 84% polyphorphoric acid were added into a 250 mL3-neck flask equipped with a condenser. The system was flashed withargon for 15 minutes before 50 mL of anhydrous chlorobenzene was added.The mixture was heated at 140° C. for 40 hours before it was cooled downto room temperature. Dichloromethane (100 mL) was added. The organicmixture was washed with saturated NaHCO₃ before the solvent was removedunder vacuum. Methanol (100 mL) was added before5,10-dimethoxy-1,6-dithia-dicyclopenta[a,f]naphthalene (2.0 g, ˜66%yield) was collected as a white solid by filtration, washed withmethanol and dried in vacuo. ¹H NMR (CDCl₃, 500 MHz): δ 7.97 (d, 2H,J=5.5 Hz), δ 7.62 (d, 2H, J=5.5 Hz), δ 7.51 (s, 2H), δ 4.18 (s, 6H).

5,10-Dimethoxy-1,6-dithia-dicyclopenta[a,f]naphthalene (1.80 g, 6.0mmol), 1.14 g (6.0 mmol) of toluene-4-sulfonic acid (CH₃C₆H₄SO₃H.H₂O),and 35 mL of 2-butyloctanol were added into a 250 mL 3-neck flaskequipped with a ondenser. The system was heated at 180° C. overnightunder argon before the mixture was cooled down to room temperature.Hexane (200 mL) was added and the organic layer was washed withsaturated NaHCO₃ before the solvent was removed under vacuum. Excess2-butyloctanol was distilled out under vacuum. Column chromatography(silica gel) with an eluent of hexane/dichloromethane (v/v, 100/4)yielded product5,10-bis-(2-butyl-octyloxy)-1,6-dithia-dicyclopenta[a,f]naphthalene as acolorless liquid (2.5 g, ˜68.5% yield). ¹H NMR (CDCl₃, 500 MHz): δ 7.96(d, 2H, J=5.5 Hz), δ 7.60 (d, 2H, J=5.5 Hz), δ 7.50 (s, 2H), δ 4.23 (d,4H, J=5.5 Hz), δ 1.99 (m, 2H), δ 1.33 (m, 32H), δ 0.96 (t, 6H, J=7.0Hz), δ 0.90 (t, 6H, J=7.0 Hz).

5,10-Bis-(2-butyl-octyloxy)-1,6-dithia-dicyclopenta[a,f]naphthalene(1.41 g, 2.3 mmol) was added into a 200 mL flask. The system wasvacuumed and backfilled with argon 3 times before 60 mL of anhydrous THFwas injected. N-Butyllithium (2.2 mL, 2.5 M in hexane, 5.09 mmol) wasadded after the mixture was cooled to −78° C. A white precipitate wasobserved after the mixture was stirred at −78° C. for 30 minutes.Stirring was continued at room temperature for one more hour before themixture was cooled down to −78° C. again. Trimethyltin chloride (1.20 g,5.75 mmol) was added in portions and stirring was continued overnight atroom temperature. Hexane (100 mL) was added and the organic layer waswashed with 150 mL of water. The aqueous layer was extracted with 100 mLof hexane twice. The combined organic layer was dried over anhydrousNa₂SO₄. Removal of solvent under vacuum yielded a white solid. Thecolorless crystalline product,5,10-bis-(2-butyl-octyloxy)-2,7-bis-trimethylstannanyl-1,6-dithia-dicyclopenta[a,f]naphthalene,(1.70 g, ˜79% yield) was obtained after recrystallization from ahexane/iso-propanol mixture. ¹H NMR (CDCl₃, 500 MHz): δ 7.80 (s, 2H), δ7.69 (s, 2H), δ 4.25 (d, 4H, J=5.5 Hz), δ 1.99 (m, 2H), δ 1.33 (m, 32H),δ 0.96 (t, 6H, J=7.0 Hz), δ 0.90 (t, 6H, J=7.0 Hz), δ 0.51 (m, 18H).

4,7-Bis-(5-bromo-4-dodecyl-thiophen-2-yl)benzo[1,2,5]thiadiazole (47.69mg, 0.06 mmol), 4,7-bis-(5-bromo-thiophen-2-yl)benzo[1,2,5]thiadiazole(9.16 mg, 0.02 mmol), and5,10-bis-(2-butyl-octyloxy)-2,7-bis-trimethylstannanyl-1,6-dithia-dicyclopenta[a,f]naphthalene(74.77 mg, 0.08 mmol), Pd₂(dba)₃ (2.93 mg, 3.2 μmol), P(o-Tol)₃ (3.90mg, 12.8 μmol) were combined in a 50 mL flask. The system was purgedwith argon before 16 mL of anhydrous chlorobenzene was added. Thereaction mixture was heated at 135° C. for 18 hours. After cooling downto room temperature, the polymer was precipitated out from 80 ml ofmethanol and further purified by a Soxlet apparatus with methanol, ethylacetate, dichloromethane. The residue weighed 49.0 mg (−81.6% yield)after removing the solvent and drying in vacuo.

Example 35 Preparation of naphthodithiophene-based donor polymer

4,7-Bis-(5-bromo-4-dodecyl-thiophen-2-yl)-5-chloro-benzo[1,2,5]thiadiazole(49.76 mg, 0.06 mmol),4,7-bis-(5-bromo-thiophen-2-yl)-5-chloro-benzo[1,2,5]thiadiazole (9.85mg, 0.02 mmol),5,10-bis-(2-butyl-octyloxy)-2,7-bis-trimethylstannanyl-1,6-dithia-dicyclopenta[a,f]naphthalene(74.77 mg, 0.08 mmol), Pd₂(dba)₃ (2.93 mg, 3.2 μmol), and P(o-Tol)₃(3.90 mg, 12.8 μmol) were combined in a 50 mL flask. The system waspurged with argon before 16 mL of anhydrous chlorobenzene was added. Thereaction mixture was heated at 135° C. for 18 hours. After cooling downto room temperature, the polymer was precipitated out from 80 ml ofmethanol and further purified by a Soxlet apparatus with methanol, ethylacetate, and dichloromethane. The residue weighed 83.0 mg (−86.9% yield)after removing the solvent and drying in vacuo.

Example 36 Preparation of2,6-bis(trimethylstannyl)-benzo[1,2-b:4,5-b′]dithiophene-4,8-(5-(2-hexyldecyl)-2-thiophenecarboxylicacid)ester

1-Iodo-2-hexyldecane (1)

Under air, triphenylphosphine (107.44 g, 410 mmol, 1.19 equiv.) andimidazole (28.9 g, 424 mmol, 1.23 equiv.) were dissolved indichloromethane (800 mL). 2-Hexyl-1-decanol (100 mL, 345 mmol., 1.00equiv.) was added to the solution, and the reaction mixture was cooledto 0° C. Iodine (103.6 g, 408 mmol., 1.18 equiv.) was added portion-wiseover 1 hour, after which the suspension was stirred at 0° C. for anadditional hour, and then at ambient temperature for 18 hours. Themixture was quenched with saturated aqueous Na₂SO₃ (150 mL), and DCM wasremoved in vacuo. Hexane (200 mL) was added to the residue, and themixture was filtered to remove salts that had precipitated. The organicmaterial was extracted with hexanes (3×300 mL), dried over Na₂SO₄,filtered through a pad of silica gel, and then concentrated in vacuo togive a clear, colorless oil (97.8 g, 82% yield). ¹H NMR (500 MHz, CDCl₃)δ 3.28 (d, J=4.6 Hz, 2H), 1.34-1.19 (m, 24H), 1.12 (b, 1H), 0.91-0.87(m, 6H).

2-(2-Hexyldecyl)thiophene (2)

A solution of thiophene (46.4 g, 551 mmol., 2.50 equiv.) and THF (300mL) was cooled to −78° C. n-Butyllithium (2.5 M in hexanes, 212 mL, 528mmol., 2.40 equiv.) was added over 1 hour. The mixture was stirred foran additional 30 minutes at −78° C. before a solution of1-iodo-2-hexyldecane (90.0 g, 220 mmol., 1.00 equiv) in THF (200 mL) wasadded slowly over 1 hour. After stirring for 1 hour at −78° C., thereaction mixture was warmed to ambient temperature and stirred for 18hours. Water (200 mL) was added and the organic material was extractedwith Et₂O (3×250 mL), washed with additional water, dried over Na₂SO₄,filtered, and concentrated in vacuo. The resulting brown residue waspurified by silica gel column chromatography (hexanes) to give a paleyellow oil (52.03 g, 77% yield). ¹H NMR (500 MHz, CDCl₃) δ 7.12 (dd,J=5.2, 1.2 Hz, 1H), 6.92 (m, 1H), 6.76 (dd, J=3.4, 0.9 Hz, 1H), 2.76 (d,J=6.7, 2H), 1.62 (b, 1H), 1.33-1.21 (m, 24H), 0.91-0.87 (m, 6H).

5-(2-Hexyldecyl)-2-thiophenecarboxylic acid (3)

2-(2-Hexyldecyl)thiophene (1.00 g, 3.24 mmol., 1.00 equiv.) and THF (24mL) were added to a 50 mL schlenk flask. The solution was cooled to 0°C. n-Butyllithium (2.5 M in hexanes, 1.36 mL, 1.05 equiv.) was thenadded over 2 minutes. The solution was stirred for 1 hour at 0° C., thenthe ice/water bath was removed and the solution was stirred for 20minutes at ambient. The solution was cooled back to 0° C. and carbondioxide (obtained by subliming dry ice submerged in THF in a separateflask placed in a 25° C. heat bath) was bubbled through the solution for30 minutes. The solution was diluted with 1 N hydrochloric acid (50 mL)and EtOAc (50 mL). The organic layer was washed with brine, dried withMgSO₄, and concentrated. Purification by silica gel columnchromatography (4:1 hexanes—EtOAc, 2% AcOH) gave a colorless liquid(1.086 g, 95% yield). ¹H NMR (500 MHz, CDCl₃) δ 7.74 (d, J=3.8 Hz, 1H),6.80 (d, J=3.8 Hz, 1H), 2.79 (d, J=6.8, 2H), 1.67 (b, 1H), 1.34-1.21 (m,24H), 0.91-0.87 (m, 6H).

5-(2-Hexyldecyl)-2-thiophenecarbonyl chloride (4)

5-(2-Hexyldecyl)-2-thiophenecarboxylic acid (1.00 g, 2.84 mmol., 1.00equiv.) and CH₂Cl₂ (5 mL) were added to a 10 mL schlenk flask. Thesolution was cooled to 0° C. Oxalyl chloride (0.60 mL, 6.5 mmol, 2.3equiv.) was then added. The ice/water bath was left in place and thesolution was stirred for 64 hours while warming to room temperature. Thereaction mixture was concentrated to a clear brown liquid (931 mg, 88%yield). ¹H NMR (400 MHz, CDCl₃) δ 7.84 (d, J=3.9 Hz, 1H), 6.87 (d, J=3.8Hz, 1H), 2.81 (d, J=6.7, 2H), 1.68 (b, 1H), 1.34-1.19 (m, 24H),0.93-0.85 (m, 6H).

4,8-Dimethoxy-benzo[1,2-b:4,5-b′]dithiophene (5)

Benzo[1,2-b:4,5-b′]dithiophene-4,8-dione (7.50 g, 34.0 mmol., 1.00equiv.), ethanol (45 mL) and water (45 mL) were added to a 250 mL 2-neckround-bottom flask fitted with a reflux condenser. NaBH₄ (3.89 g, 102mmol., 3.00 equiv.) was then added portion-wise cautiously. The reactionmixture was heated to reflux for 1 hour. The flask was removed from theheat bath and potassium hydroxide (4.39 g, 78.2 mmol., 2.30 equiv.) wasadded slowly to the reaction mixture with vigorous stirring. Thesuspension was stirred at reflux for 30 minutes before adding dimethylsulfate (16 mL, 170 mmol., 5.0 equiv.), and the suspension was refluxedfor 64 hours. The reaction mixture was cooled to room temperature anddiluted with water (75 mL) and diethyl ether (500 mL) and more water(300 mL). The organic layer was washed with brine (200 mL), dried withMgSO₄ and concentrated. The crude material was purified by silica gelcolumn chromatography (solid loading, gradient of 1:1 to 1:2hexanes-dichloromethane) to give a white solid (5.314 g, 62% yield). ¹HNMR (400 MHz, CDCl₃) δ 7.52 (d, J=5.5 Hz, 2H), 7.41 (d, J=5.5 Hz, 2H),2.81 (d, J=6.7, 2H), 4.15 (s, 6H).

2,6-Dibromo-4,8-dimethoxy-benzo[1,2-b:4,5-b′]dithiophene (6)

4,8-Dimethoxy-benzo[1,2-b:4,5-b′]dithiophene (1.00 g, 3.99 mmol., 1.00equiv.) and THF (44 mL) were added to a 100 mL schlenk flask and themixture was cooled to −78° C. n-Butyllithium (2.5 M in hexanes, 3.5 mL,8.8 mmol., 2.2 equiv.) was then added and the mixture was stirred at−78° C. for 15 minutes before removing the dry ice/acetone bath andstirring at ambient for 30 minutes. The suspension was cooled to −78° C.and carbon tetrabromide (3.18 g, 9.59 mmol., 2.40 equiv.) was added. Thedry ice/acetone bath was removed and the mixture was stirred at ambientfor 1 hour. Water and dichloromethane were added (brine was also addedto break emulsion) and the aqueous layer was extracted withdichloromethane. The organic layer was washed with brine, dried withMgSO₄ and concentrated. The crude material was purified by silica gelcolumn chromatography (solid loading, 1:1 dichloromethane-hexane) andtrituration in hexanes to give a beige crystalline solid (1.368 g, 84%yield). ¹H NMR (400 MHz, CDCl₃) δ 7.48 (s, 2H), 4.07 (s, 6H).

2,6-Dibromo-benzo[1,2-b:4,5-b′]dithiophene-4,8-diol (7)

2,6-Dibromo-4,8-dimethoxy-benzo[1,2-b:4,5-b′]dithiophene (500 mg, 1.22mmol., 1.00 equiv.) and dichloromethane (12 mL) were added to a 50 mLschlenk flask. The mixture was cooled to −78° C. and boron tribromidewas added (1.0 M solution in dichloromethane, 2.5 mL, 2.5 mmol., 2.1equiv.) slowly. The mixture was stirred for 15 minutes at −78° C. beforereplacing the dry/ice acetone bath with an ice/water bath. The reactionmixture was left to warm to room temperature while stirring for 16 hoursbefore cooling to 0° C. Water (dropwise at first, 150 mL total) andadditional dichloromethane (50 mL) were added. The dichloromethane wasremoved on the rotary evaporator and the solid was collected byfiltration. The solid was washed with water (25 mL) and dichloromethane(25 ml) to give a pale blue/green crude solid to be dried under vacuumand used in the next step without additional purification (287 mg). ¹HNMR (400 MHz, CDCl₃) δ 10.13 (s, 2H), 7.71 (s, 2H).

2,6-Dibromo-benzo[1,2-b:4,5-b′]dithiophene-4,8-(5-(2-hexyldecyl)-2-thiophenecarboxylicacid) ester (8)

2,6-Dibromo-benzo[1,2-b:4,5-b′]dithiophene-4,8-diol (150 mg, 0.395mmol., 1.00 equiv.), dichloromethane (6 mL) and triethylamine (0.22 mL,1.6 mmol, 4.0 equiv.) were added to a 25 mL 2-neck round-bottom flaskfitted with a reflux condenser. A solution of5-(2-hexyldecyl)-2-thiophenecarbonyl chloride in dichloromethane (2 mL)was then added. The flask was placed in a 45° C. heat bath and thereaction mixture was stirred at reflux for 16 hours before cooling toroom temperature, diluting with dichloromethane (60 mL) and washing withwater (60 mL). The organic layer was dried with MgSO₄ and concentrated.The crude material was purified by silica gel column chromatography(solid loading, 1:1 dichloromethane-hexanes) to give a white solid (266mg, 40% yield over two steps). m.p. 76° C. ¹H NMR (400 MHz, CDCl₃) δ7.95 (d, J=3.7 Hz, 2H), 7.32 (s, 2H), 6.93 (d, J=3.6 Hz, 2H), 2.87 (d,J=6.6, 4H), 1.74 (b, 2H), 1.40-1.21 (m, 48H), 0.94-0.85 (m, 12H). Anal.calcd. for (C₅₂H₇₂O₄S₄): C, 59.53; H, 6.92. Found: C, 59.46; H, 6.80.

2,6-Bis(trimethylstannyl)-benzo[1,2-b:4,5-b′]dithiophene-4,8-(5-(2-hexyldecyl)-2thiophenecarboxylic acid)ester (9)

2,6-Dibromo-benzo[1,2-b:4,5-b′]dithiophene-4,8-(5-(2-hexyldecyl)-2-thiophenecarboxylicacid) ester (150 mg, 0.143 mmol., 1.00 equiv.) and THF (7 mL) were addedto a 50 mL schlenk tube. The solution was cooled to −78° C. andn-butyllithium (2.5 M in hexanes, 126 μL, 0.315 mmol., 2.2 equiv.) wasadded over 2 minutes. The mixture was stirred at −78° C. for 1 hourbefore adding trimethyltin chloride (68 mg, 0.343 mmol., 2.40 equiv.).The dry ice/acetone bath was removed and the reaction was stirred atambient for 2 hours before diluting with water (30 mL) and diethyl ether(50 mL). The organic layer was washed with water (30 mL) and brine (30mL), dried with MgSO₄ and concentrated to a yellow crude oil (101 mg),which was used in the polymerization step without further purification.¹H NMR (400 MHz, CDCl₃) δ 7.99 (d, J=3.7 Hz, 2H), 7.34 (s, 2H), 6.93 (d,J=3.6 Hz, 2H), 2.88 (d, J=6.4, 4H), 1.75 (b, 2H), 1.40-1.20 (m, 48H),0.93-0.85 (m, 12H), 0.48-0.32 (m, 18H).

Example 37 Preparation of Chlorinated Repeating Nits

Chlorinated repeating units can be prepared according to the schemesbelow.

a) Repeating units comprising 3- or 4-chlorinated thienyl groups:

b) Repeating units comprising 3,7-dichlorinatedbenzo[1,2-b:4,5-b′]dithienyl groups:

See, e.g., Maguire et al., J. Med. Chem., 37: 2129-2137 (1994) forstannylation of chloro-containing thiophenes, and Lei et al., Chem. Sci.DOI: 10.1039/c3sc50245g (2013) for chlorination of bromo-containingaromatics.

Example 38 Preparation of additional4,8-bis-substituted-2,6-bis-trimethylstannanyl-1,5-dithia-s-indacenes

Various embodiments of repeating units (M^(1a)) can be prepared asfollows. Briefly, an appropriate thieno-fused starting compound can bereacted with n-butyl lithium in THF at room temperature for about 1-1.5hours before 1,5-dithia-s-indacene-4,8-dione is added. The mixture thencan be heated at about 50-60° C. for 1-2 hours before cooling to roomtemperature. This is followed by the addition of a solution of SnCl₂ inHCl/H₂O, which is heated at about 50-60° C. for about 1-3 hours beforecooling to room temperature. To functionalize the repeating unit(M^(1a)) with trimethylstannanyl groups, n-butyl lithium again is added(room temperature, about 2 hours), before trimethyltin chloride is addedin portions (room temperature).

Example 39 Synthesis of Various Thieno-Fused Starting Compounds Example39A Preparation of naphthothiophene

Both substituted and unsubstituted naphthothiophenes can be preparedfrom an appropriate phthalic anhydride using the synthetic routedescribed in JP2010053094 (reproduced above), the entire disclosure ofwhich is incorporated by reference herein.

Example 39B Preparation of benzodithiophene

Substituted and unsubstituted benzodithiophenes can be prepared via thesynthetic routes provided above.

Example 39C Preparation of benzothienothiophene

Various benzothienothiophenes can be prepared using the synthetic routedescribed above.

Example 39D Preparation of dithienothiophene

Unsubstituted dithienothiophenes can be prepared via synthetic route(a), (b) or (c) as described, respectively, in Chem. Commun. 2002, 2424;J. Mater. Chem. 2003, 13, 1324; and Chem. Commun. 2009, 1846, the entiredisclosure of each of which is incorporated by reference herein.

Substituted dithienothiophenes can be prepared via synthetic route (d),(e) or (f) as described, respectively, in J. Mater. Chem. 2007, 17,4972; Chem. Mater. 2007, 19, 4925; and Syn. Met. 1999, 987, the entiredisclosure of each of which is incorporated by reference herein.

Example 39E Preparation of thienothiophene

Substituted thienothiophenes can be prepared using the synthetic routedescribed above.

Example 39F Preparation of benzothiophene

Substituted benzothiophenes can be prepared using the synthetic routesdescribed below.

Device Fabrication Example 40 Fabrication and Characterization of OPVcells

Inverted OPVs were fabricated on ITO-covered glass that was cleaned bysonication in soap water, water, acetone and isopropanol followed bystorage in a glass oven. Immediately before deposition of theelectron-injection layer, the substrates were UV ozone treated for 20minutes in a Jelight UVO Cleaner® 42. ZnO films were prepared accordingto a previously published method. See Lloyd et al., “Influence of thehole-transport layer on the initial behavior and lifetime of invertedorganic photovoltaics,” Solar Energy Materials and Solar Cells, 95, 5,1382-1388 (2011). Donor:Acceptor (1:1 by weight) blend active layerswere spin cast from chloroform solutions. Some of the active layers wereannealed at temperatures ranging from about 80° C. to about 180° C. forabout 3-10 minutes before deposition of the top electrode. To completethe device fabrication, 8 nm of vanadium oxide (V2O₅) and 100 nm ofaluminum were successively deposited thermally under vacuum of ˜10⁻⁶Torr. The active area of the device was ˜0.09 cm². The devices were thenencapsulated with a cover glass using EPO-TEK OG112-6 UV curable epoxy(Epoxy Technology) in the glove box.

The photovoltaic characteristics of the encapsulated devices were testedin air. The current density-voltage (J-V) curves were obtained using aKeithley 2400 source-measure unit. The photocurrent was measured undersimulated AM1.5G irradiation (100 mW cm⁻²) using a xenon-lamp-basedsolar simulator (Newport 91160A 300 W Class-A Solar Simulator, 2 inch by2 inch uniform beam) with air mass 1.5 global filter. The lightintensity was set using an NREL calibrated silicon photodiode with acolor filter.

TABLE 1 JV characteristics of representative donor:acceptor blendsystems in inverted devices. All active layers were processed fromchloroform. Electron-Acceptor Polymer Electron-Donor Polymer PCE (%) Ex.3 Ex. 14 1.8 Ex. 3 Ex. 22 1.6 Ex. 3 Ex. 25 5.2 Ex. 9 Ex. 14 1.0 Ex. 9Ex. 22 0.7 Ex. 9 Ex. 25 3.2 Ex. 3 Ex. 32 5.3 Ex. 9 Ex. 32 3.8 Ex. 3 Ex.33 2.7 Ex. 8 Ex. 33 3.1

The present teachings encompass embodiments in other specific formswithout departing from the spirit or essential characteristics thereof.The foregoing embodiments are therefore to be considered in all respectsillustrative rather than limiting on the present teachings describedherein. Scope of the present invention is thus indicated by the appendedclaims rather than by the foregoing description, and all changes thatcome within the meaning and range of equivalency of the claims areintended to be embraced therein.

1. An optoelectronic device comprising a first electrode, a secondelectrode, and a photoactive layer disposed between the first and secondelectrodes, the photoactive layer comprising a polymer-polymer blendsemiconductor material, the polymer-polymer blend semiconductor materialcomprising an electron-donor polymer and an electron-acceptor polymer,wherein the electron-acceptor polymer is a copolymer comprising anaromatic fused-ring diimide unit in its backbone, and wherein theelectron-donor polymer is a copolymer comprising one or more thienyl orthienyl units and at least one electron-poor unit in its backbone. 2.The device of claim 1, wherein the electron-acceptor polymer isrepresented by Formula 1 or 2:

wherein: π-1 and π-1′ are identical or different and independently arean optionally substituted fused ring moiety; R¹ and R^(1′) are identicalor different and independently are selected from the group consisting ofa C₁₋₃₀ alkyl group, a C₂₋₃₀ alkenyl group, a C₁₋₃₀ haloalkyl group, aC₆₋₂₀ aryl group and a 5-14 membered heteroaryl group, wherein the C₆₋₂₀aryl group and the 5-14 membered heteroaryl group optionally aresubstituted with a C₁₋₃₀ alkyl group, a C₂₋₃₀ alkenyl group, or a C₁₋₃₀haloalkyl group; M^(a) and M^(a′) are identical or different andindependently are a repeat unit comprising one or more conjugatedmoieties that does not include a rylene diimide; p and q independentlyare a real number, wherein 0.1≦p≦0.9, 0.1≦q≦0.9, and the sum of p and qis about 1; and n is an integer in the range of 2 to 5,000; providedthat at least one of the following is true: (a) π-1′ is different fromπ-1, (b) R^(1′) is different from R¹, or (c) M^(a′) is different fromM^(a).
 3. The device of claim 2, wherein π-1 and π-1′ independently areselected from the group consisting of:


4. The device of claim 2, wherein the electron-acceptor polymer isrepresented by Formula 3 or 4:

wherein: R′ and R″ are identical or different and independently areselected from the group consisting of H, F, Cl, —CN, and -L-R, whereinL, at each occurrence, independently is selected from the groupconsisting of —O—, —S—, —C(O), —C(O)O—, and a covalent bond; and R, ateach occurrence, independently is selected from the group consisting ofa C₆₋₂₀ alkyl group, a C₆₋₂₀ alkenyl group, and a C₆₋₂₀ haloalkyl group;m and m′ independently are 1, 2, 3, 4, 5 or 6; and π-1, π-1′, R¹,R^(1′), p, and q are as defined in claim
 5. 5. The device of claim 2,wherein the electron-acceptor polymer is represented by Formula 5, 6, 7,or 8:

wherein R¹, R^(1′), p, q, and n are as defined in claim
 5. 6. The deviceof claim 2, wherein R′ and R^(1′) are selected from the group consistingof a branched C₃₋₂₀ alkyl group, a branched C₄₋₂₀ alkenyl group, and abranched C₃₋₂₀ haloalkyl group.
 7. The device of claim 6, wherein R¹ andR^(1′) are selected from the group consisting of:


8. The device of claim 1, wherein the electron-donor polymer has analternating push-pull structure represented by formula 9:*D-A*  (9), wherein the donor subunit (D) comprises a bridgeddithiophene moiety selected from the group consisting of abenzodithiophene moiety, a naphthodithiophene moiety, athienodithiophene moiety, and a pyridodithiophene moiety; the acceptorsubunit (A) comprises an electron-poor conjugated moiety; and either thedonor subunit (D) or the acceptor subunit (A) comprises one or morethienyl groups.
 9. The device of claim 8, wherein the donor subunit (D)comprises a bridged dithiophene moiety of the formula:

wherein R^(a), at each occurrence, independently is selected from thegroup consisting of -L′-R^(b), -L′-Ar′, and -L′-Ar′-Ar′, wherein L′ isselected from the group consisting of —O—, —S—, and a covalent bond;R^(b) is selected from the group consisting of a C₃₋₄₀ alkyl group, aC₃₋₄₀ alkenyl group, and a C₃₋₄₀ haloalkyl group; and Ar′, at eachoccurrence, independently is a 5-14 membered heteroaryl group optionallysubstituted with 1-2 R^(b) groups.
 10. The device of claim 8, whereinthe donor subunit (D) comprises a bridged dithiophene moiety selectedfrom the group consisting of:

where R^(b), at each occurrence, is a linear or branched C₅₋₄₀ alkylgroup.
 11. The device of claim 8, wherein the donor subunit (D)comprises a bridged dithiophene moiety selected from the groupconsisting of:

is selected from the group consisting of:

each of which optionally is substituted with 1-2 R^(b) groups, andR^(b), at each occurrence, independently is a C₃₋₄₀ alkyl group.
 12. Thedevice of claim 8, wherein the acceptor subunit (A) is represented bythe formula:

wherein δ represents the electron-poor conjugated moiety, and R^(c), ateach occurrence, is H or R, wherein R, at each occurrence, independentlyis selected from the group consisting of a C₆₋₂₀ alkyl group, a C₆₋₂₀alkenyl group, and a C₆₋₂₀ haloalkyl group.
 13. The device of claim 12,wherein the electron-poor conjugated moiety (δ) is an 8-14 memberedpolycyclic heteroaryl moiety comprising either at least one ring thathas two or more heteroatoms selected from N and S, and/or at least onering that is substituted with one or more electron-withdrawing groupsselected from the group consisting of F, Cl, an oxo group, a carbonylgroup, a carboxylic ester group, and a sulfonyl group.
 14. The device ofclaim 12, wherein the electron-poor conjugated moiety (δ) is selectedfrom the group consisting of:

wherein R^(d), at each occurrence, independently is selected from aC₃₋₄₀ alkyl group, a C₃₋₄₀ alkenyl group, and a C₃₋₄₀ haloalkyl group;and R^(f), at each occurrence, independently is selected from the groupconsisting of H, F, Cl, —CN, —S(O)₂—C₁₋₂₀ alkyl, —C(O)—OC₁₋₂₀ alkyl,—C(O)—C₁₋₂₀ alkyl, a C₁₋₂₀ alkyl group, a C₂₋₂₀ alkenyl group, a C₁₋₂₀alkoxy group, a C₁₋₂₀ alkylthio group, and a C₁₋₂₀ haloalkyl group. 15.The device of claim 1, wherein the electron donor polymer is a randomcopolymer having the formula 13 or 14:

wherein: R^(a), at each occurrence, is selected from the groupconsisting of -L′-R^(b), -L′-Ar′, and -L′-Ar′-Ar′, wherein L′ isselected from the group consisting of —O—, —S—, and a covalent bond;R^(b) is selected from the group consisting of a C₃₋₄₀ alkyl group, aC₃₋₄₀ alkenyl group, and a C₃₋₄₀ haloalkyl group; and Ar′, at eachoccurrence, independently is a 5-14 membered heteroaryl group optionallysubstituted with 1-2 R^(b) groups; R^(c), at each occurrence, is H or R,where R, at each occurrence, independently is selected from the groupconsisting of a C₆₋₂₀ alkyl group, a C₆₋₂₀ alkenyl group, and a C₆₋₂₀haloalkyl group; δ is selected from the group consisting of:

wherein R^(d), at each occurrence, independently is selected from aC₃₋₄₀ alkyl group, a C₃₋₄₀ alkenyl group, and a C₃₋₄₀ haloalkyl group;and R^(f), at each occurrence, independently is selected from the groupconsisting of H, F, Cl, —CN, —S(O)₂—C₁₋₂₀ alkyl, —C(O)—OC₁₋₂₀ alkyl,—C(O)—C₁₋₂₀ alkyl, a C₁₋₂₀ alkyl group, a C₂₋₂₀ alkenyl group, a C₁₋₂₀alkoxy group, a C₁₋₂₀ alkylthio group, and a C₁₋₂₀ haloalkyl group; xand y independently are a real number, wherein 0.1≦x≦0.9, 0.1≦y≦0.9, andthe sum of x and y is about 1; and n is an integer in the range of 2 to5,000.
 16. The device of claim 14, wherein R^(d), at each occurrence,independently is a linear or branched C₆₋₂₀ alkyl group; and R^(f), ateach occurrence, independently is selected from H, F, Cl, C(O)R^(e),C(O)OR^(e), and S(O)₂R^(e); where R^(e), at each occurrence,independently is a linear or branched C₆₋₂₀ alkyl group.
 17. The deviceof claim 5, wherein the electron donor polymer is an alternatingcopolymer selected from the group consisting of formula 15-24, whereinR^(b), at each occurrence, is a linear or branched C₃₋₄₀ alkyl group;R^(e), at each occurrence, is H or a C₆₋₂₀ alkyl group; and n is aninteger in the range of 5 to 5,000.
 18. The device of claim 5, whereinthe electron donor polymer is a random copolymer selected from the groupconsisting of formula 25-42, wherein R^(b), at each occurrence, is alinear or branched C₃₋₄₀ alkyl group; R, at each occurrence, is a C₆₋₂₀alkyl group; x and y independently are a real number, wherein 0.1≦x≦0.9,0.1≦y≦0.9 (0.2≦x≦0.8, 0.2≦y≦0.8), and the sum of x and y is about 1; andn is an integer in the range of 5 to 5,000.
 19. The device of claim 5,wherein the electron donor polymer is an alternating copolymer selectedfrom the group consisting of formula 43-56, wherein R^(b), R^(d), R^(e),at each occurrence, independently is a linear or branched C₃₋₄₀ alkylgroup; R^(c), at each occurrence, is H or a C₆₋₂₀ alkyl group; R^(f), ateach occurrence, independently is selected from H, F, Cl, C(O)R^(e),C(O)OR^(e), and S(O)₂R^(e); where R^(e), at each occurrence,independently is a linear or branched C₆₋₂₀ alkyl group; r is 0 or 1;and n is an integer in the range of 5 to 5,000.
 20. The device of claim1 configured as an organic photovoltaic device comprising an anode, acathode, optionally one or more anode interlayers, optionally one ormore cathode interlayers, and in between the anode and the cathode thephotoactive layer.